The Deepest Darkest Chocolate Cake

Makes 1 (9-inch) 4-layer cake, 12 to 15 servings

What You Need

Ingredients

For the deep chocolate cake:
Cooking spray
1/2 cup Dutch-processed cocoa powder
1/4 cup boiling water
2 ounces unsweetened chocolate, coarsely chopped
3/4 cup whole milk
2 cups all-purpose flour
1 teaspoon baking powder
1 teaspoon baking soda
1 teaspoon salt
2 sticks (8 ounces) unsalted butter, at room temperature
1 3/4 cups granulated sugar
4 large egg yolks
1 tablespoon vanilla extract
4 large egg whites

For the chocolate ganache frosting:
2 cups heavy cream
24 ounces bittersweet chocolate, finely chopped
2 teaspoons vanilla extract

For the chocolate drizzle and decorating:
4 ounces bittersweet chocolate, finely chopped
1/4 cup heavy cream
Chocolate sprinkles or chocolate shavings (optional)

Equipment
Measuring cups and spoons
Knife and cutting board
2 (9-inch) round cake pans
Parchment paper
Mixing bowls
Stand mixer or electric hand mixer
Wide, flat spatula
Large serrated knife
Microwave-safe bowl
Whisk
Small serving spoon

Instructions

Bake the cake:

1. Heat the oven and prep the pans. Arrange a rack in the middle of the oven and heat to 375°F. Coat 2 (9-inch) round cake pans with cooking spray and line the bottom of each pan with a parchment paper round.
2. Bloom the chocolate. Place the cocoa and water in small bowl and stir into a thick paste.
3. Heat the milk and melt the chocolate. Place the unsweetened chocolate and milk in a small saucepan over medium-high heat, stirring frequently until the chocolate is melted.
4. Add the cocoa mixture to the milk mixture. Add the bloomed cocoa mixture into the pan of warmed milk and whisk until smooth. Set aside to cool to room temperature before adding to the cake batter.
5. Whisk together the flour, leaveners, and salt. Place the flour, baking powder, baking soda, and salt in a medium bowl and whisk to combine; set aside.
6. Cream together the butter and sugar until light and fluffy. Place the butter and sugar in a stand mixer fitted with a paddle attachment. (Alternatively, use an electric hand mixer and large bowl. Beat on medium speed until light and fluffy, about 3 minutes. Stop and scrape down the sides of the bowl.
7. Add the yolks, followed by the chocolate mixture. With the mixer on low speed, add the egg yolks one at a time. Once fully incorporated, stop the mixer and scrape down the sides of the bowl. Return the mixer to low speed and slowly add chocolate-milk mixture. Beat in the vanilla.
8. Add the flour mixture. Remove the bowl from the mixer and fold the flour mixture into the cake batter — don't worry if there are a few dry spots, there's more folding ahead.
9. Whip the egg whites. Place the egg whites in a clean, large bowl. Use an electric hand mixer or a whisk to whip to soft peaks.
10. Gently fold the egg whites into the cake batter. Gently fold 1/2 of the beaten whites into the cake batter. Use a wide flat spatula and gently scoop through the batter to incorporate the egg whites. It's okay if there are some white streaks in the batter between the second and first batch of egg whites. Fold in the remaining egg whites.
11. Divide the cake batter between the pans and bake the cakes. Divide the batter evenly between the 2 pans. Bake until the cake bounces back when pressed and a skewer comes out clean, 30 to 35 minutes.
12. Cool and remove the cakes from the pan. Place the cake pans on a cooling rack and cool for 20 minutes. Flip the cakes out, remove the parchment, and place right-side up on the rack to cool completely.

Make the ganache frosting:

1. Heat the cream in the microwave. Place the cream into a microwave-safe bowl or measuring cup and microwave on high for 2 minutes. While the cream is heating, place the chocolate in a large, heatproof bowl.
2. Pour the cream over the chocolate. Pour the hot cream over the chocolate and set aside to sit for 5 minutes — the heat of the cream will melt the chocolate.
3. Whisk to combine, then cool at room temperature for 1 hour. Whisk the chocolate ganache until smooth, then set aside at room temperature to cool and thicken, about 1 hour. You want the ganache to be about as thick as room-temperature butter (soft and spreadable) before whipping.
4. Whip the cooled ganache into frosting. Beat the cooled ganache with an electric hand mixer on medium speed until it lightens in color and increases in volume, about 8 minutes.

Assemble the cake:

1. Slice the cakes in half. Use a long serrated knife to cut each cake into 2 layers. You should have 4 cake layers.
2. Fill the cakes with the whipped ganache. Set a single layer of cake on a cake plate, serving platter, cake round. Spread about 3/4 cup of the whipped ganache onto the first layer thinly and evenly. Top with second layer and more whipped ganache, and repeat until you have 3 layers of filling and 4 layers of cake.
3. Coat the cake with ganache frosting. Dump the remaining ganache on top of the cake and use a spatula to work it down the sides until the whole cake is completely frosted. Smooth the top and sides as much as possible. Don't worry — the chocolate drizzle will cover imperfections.

Make the chocolate drizzle:

1. Combine the chocolate and heavy cream in a microwave-safe bowl. Place the chocolate and cream in a microwave-safe bowl and stir to combine.
2. Microwave for 1 minute. Microwave the chocolate-cream mixture for 1 minute on HIGH.
3. Stir to combine and let cool about 5 minutes. Whisk together the chocolate and cream until smooth. Set aside until just warm to the touch, about 5 minutes.
4. Spoon the drizzle onto the edges of the cake. Use a small serving spoon to pour the drizzle onto the top edge of the cake until it drips over the edge.
5. Decorate the cake. Decorate with sprinkles or chocolate shavings if using before the drizzle sets.

Recipe Notes

• Storage: Store any leftover cake in the refrigerator for up to 4 days. Bring to room temperature before serving.
• Make ahead: The cakes can be baked up to 3 days in advance, wrapped tightly in plastic wrap, and refrigerated.