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Octopus Cake

I had so much fun making my elephant cake last week I decided to continue my animal cake series. I’ve wanted to make an octopus cake for the longest time, and today was the day!!

image of an octopus cake made with colorful cake layers, buttercream and cake decorating rice krispie

I’ve avoiding making an octopus cake for a while because I was always scared of the tentacles (or more technically “arms”).

But thanks to the help of some cake decorating-friendly rice krispies (more on that below) this octopus cake is a lot of fun to make.

Making The Face for This Little Octopus

While I’m always team buttercream, there are some situations where using a bit of fondant just makes sense.

We’ve already put so much energy into making the cake layers and buttercream from scratch, a tiny but of fondant never hurt anyone.

I used a little bit of black and white fondant to make the little face on this octopus.

Small circle cutters can help you to get the shape of the eyes just right, and I love the adorable expression they give this cake.

image of an octopus cake being frosted and smoothed using an acetate sheet

Making this Octopus Cake with Rice Krispie Treats

You read that right! A batch of cake decorating-friendly rice krispies makes this challenging cake shape so much more manageable.

By omitting the butter that is in most rice krispie treats, these rice krispies set quite firmly once they’ve cooled.

This allows you to creatively and easily shape your cake. I used the same technique to make my Patrick Star cake I highly recommend if for larger shaped cake like this.

image of an octopus cake made being made with colorful cake layers, buttercream and cake decorating rice krispie

Substitutions and Swaps – Colorful Swirled Cake Layers

This octopus birthday cake uses quite a few ingredients and I know you might not have all of them on hand. Or if you have food allergies or restrictions, I’ve got you covered.

Below are some swaps and substitutions that can be made in this octopus cake recipe.

  • All Purpose Flour – This recipe turns out best with AP flour, but you can use a gluten free flour blend or cake flour if that’s all you have on hand. I don’t recommend using straight almond flour though!
  • Granulated Sugar – I do not recommend reducing the amount of sugar or changing the type of sugar, as it will change the texture of the cake layers.
  • Unsalted Butter – If you only have salted butter on hand, you can use it in place of the unsalted butter in this recipe. Just be sure to omit the salt that this cake recipe calls for. You can also use vegan butter in its place!
  • Egg whites – If you don’t have egg whites on hand (I use the type out of the carton), you can use 4 whole eggs in place of the egg whites. Or you have an egg allergy you can use flaxseed eggs or an egg replacer.
  • Sour Cream – You can also use full fat yogurt, buttermilk, whole milk, or an alternative yogurt or milk (almond, soy, oat) if you’re dairy free.
  • Vegetable Oil – You can use any flavorless oil in this recipe. Canola or even sunflower oil would work great!
  • Vanilla Extract – Other extracts can also be used in place of the vanilla extract. Feel free to use almond, coconut, or even pistachio extract.
  • Gel food coloring – Natural food coloring (either liquid or powder) or liquid food coloring can be used if needed.
image of a purple and blue cake slice

Substitutions and Swaps – Vanilla Buttercream Frosting

  • Unsalted Butter – If you only have salted butter on hand, you can use it in place of the unsalted butter. Just be sure to omit the salt that this frosting recipe calls for. You can also use vegan butter in its place!
  • Heavy Cream – Whole milk or alternative milk (soy, almond, oat) will work fine in this frosting recipe if that’s what you have on hand.
  • Vanilla Extract – Other extracts can also be used in place of the vanilla extract. Feel free to use coconut extracthazelnut extract, or even pistachio extract.
  • Gel food coloring – Natural food coloring (either liquid or powder) or liquid food coloring can be used if needed.
image of an octopus cake being frosted and smoothed using a small offset spatula

Coloring These Swirled Cake Layers & Frosting

Coloring these cake layers is totally optional, but it creates a fun surprise when you cut into the cake!

I used gel food coloring to make these cake layers purple and blue, along with my buttercream.

Liquid food coloring can work too, but it can throw off the consistency of the cake batter and frosting if you add too much.

Sometimes it can also give your frosting a bitter taste!

highly recommend using gel food coloring. Gel food coloring is concentrated so it allows you to use less. A couple squirts will create beautiful shades.

image of colorful swirled cake layers made with purple and blue cake batter

Gel food coloring is also thicker, so it won’t change the consistency of the cake batter.  Americolor and Chef Master are my go-to brands of gel food coloring and I order them on amazon.

Natural food coloring (either liquid or powder) can be used in place of the gel food coloring! The colors won’t be quite the same, but it will still be beautiful.

Tips for Making the Best Octopus Cake:

  • Properly measure your flour (spoon into the cup measure, then level) or use a kitchen scale to measure your dry ingredients.
  • Use gel food coloring to create vibrant colors of frosting without throwing off the consistency of the frosting or giving it a bitter taste.
  • Ingredients at room temp mix together better, so be sure you set out any cold ingredients ahead of time.
  • Mix your cake batter just until the ingredients are incorporated. This will ensure your cake layers are tender and soft.
  • Use an acetate sheet to help you get your final coat of frosting super smooth.
image of an octopus cake being frosted and smoothed using an acetate sheet
  • Chill your cake layers in the freezer for about 20 minutes before assembling the cake. This makes it easier to stack and frost.
  • Make this octopus cake vegan or dairy free if needed! Use your favorite type of dairy free milk to replace the buttermilk and heavy cream and use vegan butter sticks in place of the butter. For the eggs I recommend using an egg replacer like this.
  • Be patient and give yourself lots of time! Sculpted cakes like this can be challenging. Take your time smoothing the frosting and adding on the details to this cake.
image of an octopus cake close up to show the detail on its arm or tentacle

Making This Octopus Cake in Advance & Storage Tips

Make your cake layers in advance and freeze them. It breaks the process up and makes it more approachable.

Make your frosting ahead of time too or save any leftover frosting. It can be stored in an airtight container in the fridge for up to a month. Or store it in the freezer for up to 3 months! Be sure to give it a good stir once it thaws to get the consistency smooth again.

A frosted cake can last in the fridge for up to a week. The buttercream locks in all the moisture, keeping the cake fresh and delicious.

If you cut into the cake and have leftovers, use any remaining frosting to cover the cut section to keep it moist. It can be stored in the fridge like this for up to a week.

image of an octopus cake made for a birthday party with a party hat

Let Me Know What You Think!

If you try this octopus birthday cake recipe, I’d love to hear what you think of it! Let me know by leaving a rating below.

If you plan to share on social media, you can tag me @chelsweets and use #chelsweets so that I can see your amazing creations on social media.

image of an octopus cake made with colorful cake layers and homemade buttercream

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Yield: 24

Octopus Cake

image of an octopus cake made with colorful cake layers and homemade buttercream

This octopus cake is just fun to make as it is eat! It's made with colorful swirled cake layers and frosted with buttercream frosting.

Prep Time 15 minutes
Cook Time 34 minutes
Additional Time 2 hours
Total Time 2 hours 49 minutes

Ingredients

Swirled Cake Layers

  • 3 cups all-purpose flour (390 grams)
  • 3 cups granulated sugar (600 grams)
  • 2 1/2 tsp baking powder (10 grams)
  • 1 tsp salt (6 grams)
  • 1 cup unsalted butter, room temperature (226 grams) - 2 sticks
  • 1 cup pasteurized egg whites from a carton (or about 7 egg whites) (235 grams)
  • 1 1/2 cups sour cream, room temperature (380 grams)
  • 2 Tbsp vegetable oil (28 grams)
  • 2 tsp vanilla extract (8 grams)
  • blue and purple gel food coloring - optional

Vanilla Buttercream Frosting

  • 3 cups unsalted butter, room temperature (678 grams)
  • 1 Tbsp vanilla extract (12 grams)
  • 1 tsp salt (6 grams)
  • 11 cups powdered sugar (1375 grams)
  • 1/3 cup heavy cream (or whipping cream) (75 grams)
  • blue and purple gel food coloring - optional

Rice Krispie Treats - Octopus Legs

  • 5 cups mini marshmallows (250 grams)
  • 7 cups puffed rice cereal (90 grams)

Octopus Cake Decoration

Instructions

Step 1: Make the Colorful Cake Layers

  1. Preheat oven to 350°F / 175 C. Grease and line two 7-inch cake pans, two 6-inch cake pans and set aside.
  2. Mix together 3 cups all purpose flour, 3 cups sugar, 2 1/2 tsp baking powder and 1 tsp salt in a stand mixer with a paddle attachment or hand mixer on a low speed until combined.
  3. Mix in 1 cup of unsalted butter slowly into the dry ingredients on a low speed. Continue to mix until no large chunks of butter remain and the mixture looks crumbly.
  4. Pour in 1 cup of egg whites and mix on low until just combined.
  5. Mix in 1 1/2 cups sour cream on a low speed, 2 Tbsp of vegetable oil and 2 tsp of vanilla extract. Mix at a low speed until incorporated.
  6. Scrape down the sides of the bowl with a rubber spatula then beat on a low speed for about 30 seconds to make sure everything is properly mixed together.
  7. Divide the batter evenly between three bowls and color them purple, light blue and and dark blue using gel food coloring.
  8. Add spoonfuls the colorful batter into the prepared pans, then use a small offset spatula or a butter knife to swirl the batter together.
  9. Bake the cake layers 34-36 minutes, or until a toothpick comes out with a few moist crumbs. Rotate the pans halfway through baking to help them bake more evenly.
  10. Once the cake layers are out of the oven, run a small offset spatula around the edges of the pans to help separate the cake layer from the pan.
  11. Allow the layers to cool in the pan for about 15 minutes, then flip them onto a wire rack to finish cooling.
  12. Once the cake layers have finished cooling use a serrated knife to level the tops and set the cake layers aside.
  13. Use a serrated knife to trim the edge of one of the 6-inch cake layers to give the octopus head a rounder shape.
  14. If you're making these cake layers in advance, wrap and freeze them like this. When you're ready to assemble the cake, unwrap the frozen layers and allow them to thaw for about 30 minutes before you plan to frost the cake.

Step 2: Make the Vanilla Buttercream Frosting

  1. While the cake layers bake and cool, make the buttercream frosting.
  2. Beat 3 cups of butter on a medium speed for 30 seconds with a paddle attachment or hand mixer until smooth.
  3. Add in 1 Tbsp of vanilla extract and 1 tsp of salt and mix on a low speed.
  4. Slowly mix in 11 cups of powdered sugar on a low speed. Add 1/3 cup of heavy cream half way through to make it easier to mix.
  5. Once fully mixed and has reached the desired consistency, beat on low until for a couple extra minutes to make the frosting super smooth and to push any extra air out of the frosting.
  6. If the frosting is too thick, add in additional cream (1 Tablespoon at a time). If the frosting is too thin, add in more powdered sugar (quarter of a cup at a time).
  7. Wait to color the frosting until the cake is crumb coated. Cover the buttercream with plastic wrap to prevent crusting, then set aside.

Step 3: Assemble this Octopus Cake

  1. Stack and frost cake layers on a 10-inch greaseproof cake board using a dab of frosting to help stick the first cake layer to the board.
  2. Add an even layer of buttercream between each cake layer with a large offset spatula, and stack them in the following order: 6-inch, 7-inch, 7-inch, trimmed 6-inch.
  3. Spread a thin coat of frosting around the the cake to fully cover the cake layers. Smooth using a bench scraper and/or acetate sheet, then chill the cake in the fridge (20 minutes) or freezer (10 minutes) until the frosting is firm to the touch.

Step 4: Make the Octopus Legs with Rice Krispie Treats

  1. While the crumb coat chills, make the cake-decorating friendly rice krispies to create our octopus arms.
  2. Place 5 cups of mini marshmallows in a heatproof bowl and heat in the microwave for 30 seconds at full power.
  3. Stir then heat in 15 second intervals until the marshmallows are melted (mine usually take a total of 1 minute to melt fully).
  4. Pour in 7 cups of rice krispies or puffed rice cereal and stir until the cereal is fully coated in melted marshmallows.
  5. Grease your hands with cooking spray then shape 8 legs by compacting the rice krispies into elongated triangles. Place the legs against the cake as you make them to make sure they're proportionate, shaped properly, and will all fit around the cake.

Step 5: Decorate this Octopus Cake

  1. Press the rice krispie treat legs into place around the base of the chilled cake. They should still be slightly warm and should stick in place with a bit of pressure. If they're not sticking, use a little extra buttercream to keep them in place.
  2. Scoop 1/2 cup of frosting into a bowl and color it a light shade of purple with gel food coloring. Place this frosting a small piping and set aside. Color the remaining buttercream blue with gel food coloring.
  3. Add a second, thicker layer of blue buttercream around the cake and top of the rice krispies. Smooth using a small offset spatula and an acetate sheet.
  4. Pipe the light purple buttercream underneath each rice krispie tentacle, and smooth using a small offset spatula and an acetate sheet.
  5. Chill the cake again in the fridge (20 minutes) or freezer (10 minutes) until the second coat of frosting firms up.
  6. If desired, color the leftover purple frosting a deeper shade of purple and place in a piping bag fit with a small round piping tip (or just snip the end of the bag to create a small hole). Pipe small circles underneath each of arms over the light purple frosting.
  7. Place the fondant facial features on the chilled cake with a small dab of buttercream.
  8. Let the cake sit out at room temperature for 1-2 hours before serving to make it easier to cut.

Notes

Tips for Making The Best Octopus Cake

  • Try to be patient and give yourself lots of time! Sculpted cakes like this can be challenging. Take your time smoothing the frosting and adding on the details to this cake.
  • Be sure to properly measure your flour (spoon into the cup measure then level) or use a kitchen scale to measure your dry ingredients.
  • Use gel food coloring to create vibrant colors of frosting without throwing off the consistency of the frosting or giving it a bitter taste.
  • Ingredients at room temp mix together better, so be sure you set out any cold ingredients ahead of time.
  • Mix your cake batter just until the ingredients are incorporated. This will ensure your cake layers are tender and fluffy.
  • Chill your cake layers in the freezer for about 20 minutes before assembling the cake. This makes it easier to stack and frost.
  • Make this octopus cake vegan or dairy free if needed! Use your favorite type of dairy free milk to replace the buttermilk and heavy cream, and use vegan butter sticks in place of the butter. For the eggs I recommend using an egg replacer like this.
  • Use an acetate sheet to help you get your final coat of frosting super smooth.

Making this Cake in Advance

Make your cake layers in advance and freeze them. It breaks the process up and make it more approachable.

Make your frosting ahead of time too or save any leftover frosting! It can be stored in an airtight container in the fridge for up to a month or in the freezer for up to 3 months. Be sure to give it a good stir once it thaws to get the consistency nice and smooth again.

A frosted cake can last in the fridge for up to a week, or in the freezer for up to a month. The buttercream locks in all the moisture, keeping the cake fresh and delicious!

If you cut into the cake and have leftovers, use any remaining frosting to cover the cut section to keep it moist and store in the fridge for up to a week.

Nutrition Information

Yield

24

Serving Size

1

Amount Per Serving Calories 687Total Fat 35gSaturated Fat 20gTrans Fat 0gUnsaturated Fat 13gCholesterol 86mgSodium 297mgCarbohydrates 92gFiber 0gSugar 78gProtein 4g

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