Hot Cocoa Fudge Cake

5 from 3 ratings

Hot Cocoa Fudge Cake

This hot cocoa cake is made with moist chocolate cake layers that are filled with thick layers of milk chocolate ganache and gooey, homemade marshmallow fluff. It's a rich, perfectly decadent dessert that will have you going back for more.

Prep Time1 15

Cook Time25

Additional Time30

Total Time2 10

Course: Cakes

Cuisine: American

Servings: 24 servings

Calories: 584kcal

Author: Chelsey White

Equipment

Rubber Spatula
3 8-inch cake pans
Parchment Paper
10-inch Greaseproof Cake Board or a Flat Plate
Stand Mixer or Hand Mixer
Whisk
Scale (optional)

Ingredients

Milk Chocolate Ganache

1 1/2 cups heavy whipping cream 360g
5 1/2 cups milk chocolate chips 975g
3/4 cup (1 1/2 sticks) unsalted butter, room temperature 170g
6 Tbsp light corn syrup - optional 120g
3/4 tsp fine salt 4g

Marshmallow Fluff

1/3 cup water 80g
1/2 cup granulated sugar 100g
1/2 cup light corn syrup 160g
2 large egg whites, room temperature 60g
1/3 tsp cream of tartar
2 tsp vanilla extract or vanilla bean paste 10g

Chocolate Cake Layers

2 cups all-purpose flour 260g
2 cups granulated sugar 400g
3/4 cup unsweetened cocoa powder, sifted 75g
2 tsp baking powder 8g
1 1/2 tsp baking soda 9g
1 tsp fine salt 6g
1 cup water, warm 240g
1 cup buttermilk, room temperature 240g
1/2 cup vegetable or canola oil 110g
2 large eggs, room temperature 112g
1 tsp vanilla extract or vanilla bean paste 4g

Hot Cocoa Simple Syrup

1/2 cup water 120g
1/2 cup granulated sugar 100g
2 Tbsp sweetened hot cocoa mix

Instructions

Milk Chocolate Ganache (for the filling & frosting)

Heat 1 1/2 cups of heavy cream in a large, heatproof bowl in the microwave in 30-second intervals, stirring as needed, until it just begins to bubble and steam. If you don't have a microwave, heat the cream in a small saucepan over medium heat until it just begins to steam and bubble.
Gently pour 5 1/2 cups (975g) of milk chocolate chips into the hot heavy cream. Make sure the chips are fully covered with cream. Let the mixture sit for 1 minute. If you prefer dark (60–65% cocoa) chocolate, use 4 cups (720g) of dark chocolate chips and 3 cups of heavy cream instead.
Stir slowly until the cream and chocolate combine and the mixture is smooth. If any bits of chocolate aren't fully melted, microwave at half power in 10- to 15-second intervals, stirring well between intervals, until smooth.
Then mix in 3/4 cup (1 1/2 sticks) of room-temperature unsalted butter, 6 Tbsp (3/8 cup) of light corn syrup (optional), and 3/4 tsp of fine salt until combined.
Pour the mixture into a shallow, wide tray to help it cool faster, then cover it with plastic wrap to prevent the ganache from forming a skin. Set aside to let it cool to room temperature.

Marshmallow Fluff

Make the marshmallow fluff shortly before assembling the cake, after the cake layers, simple syrup, and ganache are ready. Combine 1/3 cup (80g) water, 1/2 cup (100g) granulated sugar, and 1/2 cup (160g) light corn syrup in a medium saucepan. Stir to combine, then place a candy thermometer in the pan and heat over medium-high. Avoid stirring once the syrup begins heating to prevent crystallization.
Wipe the bowl and whisk of a stand mixer with lemon juice or vinegar to remove any grease. Add 2 room-temperature egg whites (about 60g) and 1/3 tsp cream of tartar.
When the sugar syrup reaches 225°F (107°C), whip the egg whites on medium-high speed until soft peaks form, about 3–4 minutes.
When the syrup reaches 240°F (116°C), remove it from the heat. With the mixer running on medium speed, carefully pour the hot syrup into the egg whites in a thin, steady stream between the whisk and the side of the bowl.
Increase the mixer speed to medium-high and whip for 7–8 minutes, until the marshmallow fluff is thick, glossy, and fluffy. Add 2 tsp vanilla extract and continue whipping until the fluff cools to room temperature. Use promptly to fill the cake, since the fluff is easiest to spread when freshly made.

Chocolate Cake Layers

Preheat oven to 350°F/175°C. Line three 8-inch cake pans with parchment paper rounds and spray the sides with nonstick baking spray. Set aside.
Sift or whisk together 2 cups flour, 2 cups granulated sugar, 3/4 cup unsweetened cocoa powder, 2 tsp baking powder, 1 1/2 tsp baking soda, and 1 tsp fine salt in a large bowl. Set aside.
In a separate, large bowl, add 1 cup warm water, 1 cup buttermilk, 1/2 cup oil, 2 eggs, and 1 tsp vanilla and whisk together until fully incorporated.
Whisk the dry ingredients into the wet ingredients until they're just combined, and the batter is smooth.
Pour the batter evenly (about 475g or about 2 cups per pan if you're making 3 layers) between the 3 cake pans. Bake for 24-26 minutes, or until a toothpick comes out with a few moist crumbs.
Let the pans cool for 10 minutes, then run a small offset spatula around the perimeter of the pan to separate the cake from the pan.
Place the cake pans into the freezer for 30 minutes to accelerate the cooling process. This helps lock in the steam and makes the layers extra moist. If you don't have room in the freezer, place the cake pans on a wire rack and let them cool fully before removing them.
Once the layers are fully cooled, carefully flip the pans and remove the layers. These cake layers bake up pretty flat, so leveling them is optional, but I like to level them with a serrated knife to make the cake easier to fill and frost.
If you make these cake layers in advance, let them thaw for about 15 minutes before making the cake. The cake layers should still be slightly cold to the touch, which will make it easier to assemble the cake. Do not add the simple syrup before freezing the layers; brush on the cooled simple syrup right before assembling the cake.

Hot Cocoa Simple Syrup

Pour 1/2 cup of water and 1/2 cup of granulated sugar into a small saucepan. Cook over medium heat, and stir continuously until the mixture just starts to boil. It usually takes about 3 minutes for my simple syrup to reach a boil. At this point, the sugar should have completely dissolved, and the mixture should look clear.
Remove from the heat and stir in 2 Tbsp of hot cocoa mix until fully combined. Pour into a separate container and set aside to cool to room temperature. Brush this cooled simple syrup onto the cake layers just before adding the ganache and marshmallow fluff. If making the layers ahead, do not soak them before freezing.

Hot Cocoa Fudge Cake Assembly

Place the first cake layer on a greaseproof cake board or large flat plate, using a small dab of chocolate ganache to keep it in place. Brush the layer with about a third of the cooled hot cocoa simple syrup.
Place about 1 cup of room-temperature ganache in a piping bag and seal the top with a rubber band. Cut a 3/4-inch opening at the base of the bag.
Spread about 1 1/4 cups (325g) of room-temperature chocolate ganache on the first cake layer, then pipe a ring of ganache around the edge of the cake and fill it with about 1 1/2 cups (about 135g) of marshmallow fluff.
Add the second cake layer and brush it with simple syrup, then add the chocolate ganache and marshmallow fluff to the second cake layer. Place the final cake layer upside down on top to make it easier to frost and minimize crumbing. Brush the top with the remaining simple syrup. Then chill the cake for about 15 minutes in the freezer or 30 minutes in the fridge, or until the filling is firm.
Whip the remaining room-temperature chocolate ganache with a hand mixer or stand mixer on a high speed for 1-2 minutes, or until the mixture becomes lighter in color and increases in volume.
Cover the chilled cake with the whipped chocolate ganache. Use a large offset spatula or the back of a spoon to swirl the remaining marshmallow fluff into the whipped ganache for a pretty, marbled finish, then dig in!

Video

Notes

Make Ahead and Freezing Tips

Bake the chocolate cake layers, cool them completely, then wrap tightly and freeze them without the hot cocoa simple syrup. Brush the simple syrup onto the cake layers right before assembling.

The chocolate ganache can be made ahead of time and stored in airtight containers in the fridge for up to a week or in the freezer for up to 3 months. Let it sit at room temperature for a few hours to bring it back to the proper consistency before assembling the cake.

A cake like this can be stored in the fridge for up to 3 days, but it is best enjoyed on the first or second day.

If you do refrigerate the cake, let it sit at room temperature for about an hour before serving so the ganache has time to soften.

For the best texture, make the marshmallow fluff the day you plan to assemble the cake rather than preparing it ahead of the cake layers. It can start to lose its structure as it sits.

Nutrition