Chocolate Peanut Butter Ganache Cake
Ingredients
Cake
1 3/4 cups all-purpose flour
1 cup packed dark brown sugar
1 cup sugar
1 cup unsweetened cocoa powder
1 1/2 teaspoons baking powder
1 1/2 teaspoons baking soda
1 teaspoon salt
2 large eggs, at room temperature
1 cup sour cream, at room temperature
1/2 cup vegetable oil
1 tablespoon pure vanilla extract
1 cup boiling water
2 teaspoons instant espresso powder
4 ounces bittersweet chocolate (60% cacao), finely chopped
Filling & Frosting
2 sticks unsalted butter soft but cool (about 65°F)
1 Cup commercial creamy peanut butter
4 Tablespoons honey, corn syrup
1/4 teaspoon (1g) Diamond Crystal kosher salt; for table salt, use half as much by volume or use the same weight
2 teaspoon (5g) vanilla extract, plus more if needed
3 Cups powdered sugar plus 2-3Tbsp for whip cream
1 pint Heavy Cream
Ganache Topping
8 ounces semisweet chocolate, finely chopped
1 cup heavy cream, hot but not boiling
Instructions
Cake
For the Cake: Adjust oven rack to middle position and preheat oven to 350°F. Lightly spray two 9-inch round cake pans with baking spray. Line pans with parchment paper rounds and spray once again with baking spray.
In large bowl, whisk together flour, brown sugar, sugar, cocoa powder, baking powder, baking soda, and salt. In medium bowl, whisk together eggs, sour cream, oil, and vanilla. Add egg mixture to flour mixture and stir until mixture is a thick paste.
Stir espresso powder into boiling water, and whisk mixture into cake batter until smooth.
Place chocolate in small bowl and microwave until smooth and melted, 1 to 2 minutes, stopping microwave to stir chocolate every 20 seconds. Stir melted chocolate into batter. (See Notes)
Scrape batter into prepared pans. Bake until cake tester inserted in center of cakes comes out clean, 20 to 25 minutes. Transfer cakes to cooling rack and cool in pans 10 minutes. Turn cakes out directly onto racks, peel off and discard parchment, then invert cakes so tops are facing up. Cool completely, about 1 hour.
Filling & Frosting
Whip 1 Pint heavy cream with 2-3 Tbsp powdered sugar until it forms whisps in peaks.
Combine butter, peanut butter, honey, salt, and vanilla in the bowl of a stand mixer fitted with a paddle attachment. Mix on medium speed until creamy and pale, about 3 minutes, then reduce speed to low and sprinkle in powdered sugar, a little at a time. After the last addition, increase speed to medium and continue beating until creamy and light, about 3 minutes. Scrape bowl and beater with a flexible spatula, then continue beating a minute more. Then fold in Whip Cream from Step 1. If you like, adjust to taste with more vanilla or salt. Use immediately. Frosted desserts will keep up to 1 week at room temperature
Ganache Topping
Put the chocolate in a medium bowl. Pour the hot cream over it and leave undisturbed for 1 minute. Stir gently, until the chocolate is melted and smooth. Let cool for 10 minutes.
Build the cake
Put a layer of filling on top of one cake, and the pour ganache on top to within 1" of the edge. Place second cake on top and complete frosting the cake. Pouring the ganache over the top of the cake until it starts to drip over the sides a little. Refrigerate at least 5 hours, preferably overnight.
