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image of a sloth birthday cake made with chocolate cake layers and chocolate peanut butter buttercream
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4.94 from 15 ratings

Sloth Cake

This sloth cake cake is just as adorable as it is delicious! It's made with tender chocolate cake layers and frosted with chocolate and peanut butter buttercream frosting.
Prep Time15 minutes
Cook Time30 minutes
Additional Time2 hours
Total Time2 hours 45 minutes
Course: Cakes
Cuisine: American
Servings: 24
Calories: 732kcal
Author: Chelsey White

Ingredients

Chocolate Cake Layers

  • 1 cup (2 sticks) unsalted butter, room temperature 226g
  • 2 1/2 cups granulated sugar 500g
  • 4 large eggs, room temperature 224g
  • 1 cup hot coffee or water 240ml
  • 1 cup buttermilk, room temperature 240ml
  • 1 cup unsweetened cocoa 80g
  • 3 cups self-rising cake flour 360g

Chocolate Buttercream Frosting

  • 3 cups unsalted butter, room temperature 678g
  • 1/2 cup creamy peanut butter 120g
  • 1 Tbsp vanilla extract or vanilla bean paste 12ml
  • 1 tsp fine salt 6g
  • 10 cups powdered sugar 1250g
  • 1/3 cup heavy whipping cream, room temperature 80g
  • 1/2 cup unsweetened cocoa powder, sifted 40g
  • 1/4 cup chopped dark chocolate or chips, melted and cooled 45g

Rice Krispie Treats - Sloth Arms and Legs

  • 2 cups mini marshmallows 100g
  • 3 cups puffed rice cereal 75g

Sloth Cake Decoration

Instructions

Step 1: Make the Chocolate Cake Layers

  • Begin by preheating the oven to 350 F / 175 C.
  • Line six 6-inch round cake pans with parchment rounds and spray with non-stick baking spray.
  • Add 1 cup butter and 2 1/2 cups sugar into the bowl of a stand mixer. Mix on high for 1 minute with a whisk attachment or with a hand mixer until the mixture becomes light in color.
  • Add in 4 large eggs, two at a time. Mix on a medium high speed until they're fully incorporated.
  • In a separate bowl, combine 1 cup of hot coffee, 1 cup of buttermilk, and 1 cup of cocoa powder. Whisk until smooth.
  • Next, mix 1 cup of self-rising cake flour into the butter/egg mixture on a low speed. Scrape the sides of the bowl with a rubber spatula to ensure the flour is fully incorporated.
  • Pour in half of the buttermilk/cocoa mixture and mix on a low speed.
  • Repeat with the remaining cake flour and cocoa mixture.
  • After adding in the last cup of self-rising cake flour, mix on low until the flour is just incorporated.
  • Pour the batter evenly between the prepared pans. I like to use a kitchen scale to ensure each pan has the same amount of batter.
  • Bake for 30-33 minutes or until a toothpick comes out with a few moist crumbs. Rotate pans halfway through to help them bake evenly.
  • Allow the layers to cool in the pan for about 15 minutes, then flip them onto a wire rack to finish cooling.
  • Once the cake layers have finished cooling use a serrated knife to level the tops and trim the layers to make them easier to shape into the sloth's body and head (see photos above). Set the cake layers aside.
  • If making your 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 20 minutes before you plan to frost the cake.

Step 2: Make the Chocolate Peanut Buttercream Frosting

  • While the cake layers bake and cool, make the chocolate peanut butter frosting.
  • Beat 3 cups of butter and 1/2 cup of peanut butter on a medium speed for 30 seconds with a paddle attachment or hand mixer until smooth.
  • Add in 1 Tbsp of vanilla extract and 1 tsp of salt and mix on a low speed.
  • Slowly mix in 10 cups of powdered sugar on a low speed. Add 1/3 cup of heavy cream halfway through to make it easier to mix. Scrape the sides of the bowl as needed.
  • Once the frosting is smooth 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.
  • 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 (1/4 cup at a time).
  • Place 1/3 of the peanut butter frosting in a separate bowl, and cover with plastic wrap then set aside.
  • Mix 1/2 cup of cocoa powder into the remaining buttercream and mix on a low speed until it's fully incorporated. Add an additional 2 Tbsp of heavy cream to thin the frosting, then scoop 1/2 cup of buttercream into a separate bowl. Cover the remaining chocolate peanut butter buttercream with plastic wrap then set aside.
  • Add 1/4 cup of melted and cooled dark chocolate to the remaining 1/2 cup of chocolate peanut butter buttercream. Stir until smooth, then place in a small piping bag. Seal the top of the bag with a rubber band and set aside.

Step 3: Assemble this Sloth Cake

  • Before you start to make the cake, use the black and white fondant to create the sloth's eyes, nose, mouth, and nails / claws.
  • Place the fondant pieces on a wire rack to allow them to dry and firm up while you assemble the cake.
  • Stack and frost the cake layers on a 10-inch greaseproof cake board or cake drum using a dab of frosting to help stick the first cake layer to the board.
  • Spread an even layer of peanut butter buttercream between each cake layer with a large offset spatula. Make sure to save 1/2 cup of peanut butter frosting to make the sloth's face.
  • Insert either a thick plastic straw (like a bubble tea straw) or a wooden dowel through the center of the cake layers to help stabilize them.
  • Spread a thin coat of chocolate peanut butter frosting around the cake to fully cover the cake layers. Smooth using an acetate sheet then chill the cake in the fridge (30 minutes) or freezer (10 minutes) until the frosting is firm to the touch.

Step 4: Make the Arms & Legs with Rice Krispie Treats

  • Place 2 cups of mini marshmallows in a heatproof bowl and heat in the microwave for 45-60 seconds at full power. They should be melted at this point and easy to stir. If not, heat in additional 15 second intervals until melted.
  • Pour in 3 cups of rice krispies or puffed rice cereal and stir until the cereal is fully coated in melted marshmallows.
  • Grease your hands with cooking spray then shape two thin front legs, two thick hind legs and a small tail with the rice krispie mixture. Place the arms, legs and tail next to the cake as you make them to ensure they are proportionate and shaped properly.

Step 5: Decorate this Sloth Cake

  • Press the rice krispie treat arms, legs and tail into place on the chilled cake.
  • Spread an even layer of the chocolate peanut buttercream over the rice krispies.
  • Use the reserved peanut butter frosting to make circle on the front of the sloth's head to create its face. Pipe two eye patches using the double chocolate peanut butter frosting (the darkest frosting). Then carefully press the eyes, nose and mouth into place.
  • Place the remaining chocolate peanut butter buttercream in a large piping bag fit with a small grass piping tip and pipe buttercream fur all over the cake and around the face. Take breaks as needed, this is the most time-consuming part of decorating this cake!
  • The final step is to press the fondant nails/claws into place.
  • Chill the cake again in the fridge (20 minutes) or freezer (10 minutes) until the second coat of frosting firms up.
  • If making this cake in advance, let the cake sit at room temperature for 1-2 hours to thaw before serving to make it easier to cut.

Video

Notes

Tips for Making The Best Sloth Cake:

  • Properly measure your flour (spoon into the cup measure, then level) or use a kitchen scale to measure your dry ingredients.
  • Ingredients at room temp mix together better. Set out any cold ingredients ahead of time.
  • If you don't have 6, 6-inch pans, bake as many layers as you can at a time and leave the remaining batter out at room temperature, covered with a towel. After the first batch of layers has baked and cooled a bit, bake the next round of layers.
  • 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 sloth 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.
  • Insert a thick bubble tea straw or wooden dowel through the layers once they're stacked to help keep the cake stable as you decorate it.
  • Shape the fondant nails before you start assembling the cake. This will give them a chance to firm up before you have to add them to your cake.
  • If your hands run hot, wrap a paper towel or thin kitchen towel around your piping bag to prevent the transfer of heat from your hands into the frosting.
  • Take breaks as you pipe on the buttercream fur to prevent hand cramps and keep your sanity!

Making this Cake in Advance

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 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

Serving: 1 | Calories: 732kcal | Carbohydrates: 96g | Protein: 6g | Fat: 38g | Saturated Fat: 21g | Polyunsaturated Fat: 13g | Cholesterol: 118mg | Sodium: 178mg | Fiber: 2g | Sugar: 71g