8 oz (230 g) peanut butter cups; 4 oz cut into 1⁄2-in pieces, 4 oz coarsely
Freshly mixed batter for one 10-in (25-cm) Devil’s Food Cake layer (recipe below)
Peanut Butter Mousse
6 oz cream cheese, at room temperature
3⁄4 c up creamy peanut butter, at room temperature
3⁄4 c up powdered (icing) sugar
1 c up cold heavy (double) cream
1 tsp vanilla extract (essence)
2 c ups (480 ml) ganache (recipe below), cooled until thickened but pourable
- Preheat the oven to 350°F (180°C/gas mark 4). Butter the bottom and sides of a 10-in (25-cm) round cake pan. Line the bottom with parchment (baking) paper and butter the paper.
- Use a rubber spatula to stir the 4 oz (115 g) cup of peanut butter pieces into the cake batter. Pour the batter into the prepared pan. Bake until the top feels firm when lightly touched and a toothpick inserted in the center comes out clean, about 40 minutes. Cool the cake in the pan on a wire rack for 10 minutes.
- Use a small, sharp knife to loosen the cake from the sides of the pan, and invert the cake onto the wire rack. Carefully remove the paper, then place it loosely on the cake. Let the cake cool thoroughly, then discard the paper.
- To make the peanut butter mousse: In a large bowl, using an electric mixer on medium speed, beat the cream cheese and peanut butter until smoothly blended. On low speed, mix in the powdered (icing) sugar until it is incorporated. The texture will not look completely smooth. Set aside.
- In a clean large bowl, using clean beaters, beat the cream and vanilla on medium-high speed until firm peaks form. Whisk about one-third of the whipped cream into the peanut butter mixture. Use a rubber spatula to gently but thoroughly fold in the remaining whipped cream. The mousse will be smooth.
- Invert the cake onto a serving plate so that it is top up. Leaving a 1-in (2.5-cm) plain edge around the top of the cake, use a small, sharp knife to cut out the center in one piece to create a cavity about 1 in (2.5 cm) deep. Break the removed cake into pieces about 1 in (2.5 cm). Use a metal spatula to spread about one-third of the mousse in the hollowed-out center of the cake. Put the cake pieces over the mousse, mounding them toward the center. Spread the remaining mousse over the cake pieces. It will cover the cake. Refrigerate the cake until the mousse is firm, about 30 minutes.
- Use a spatula to spread the ganache over the top and sides of the cake. Scatter the 4 oz (115 g) chopped peanut butter cups over the ganache. Use a large, sharp knife to cut the cake, carefully wiping it clean after cutting each slice. Serve cold.
The cake can be covered and refrigerated for up to 2 days.
Makes 12 to 14 servings
Mixing time 30 minutes for cake, mousse, and ganache
Baking 350°F (180°C/gas mark 4) for about 40 minutes