Servings: 8

Prep time: 25 minutes

Total time: 2 hours

Ingredients

for the chocolate caramelized puffed rice:

• 2 cups|70 grams puffed rice

• 2 tablespoons|35 grams light corn syrup

• 1 tablespoon + ¾ teaspoon|18 grams granulated sugar

• 2 ½ ounces|70 grams milk or dark chocolate

for the peanut butter mousse:

• 1 tablespoon + ½ teaspoon|11 grams unflavored powdered gelatin

• ¼ cup|55 grams cold water

• ⅔ cup|160 grams whole milk

• 5 large egg yolks

• ½ cup|100 grams granulated sugar

• 1 cup|225 grams creamy peanut butter

• 1 ⅔ cups|400 grams whipping (heavy) cream

for the dark chocolate ganache:

• ¾ cup + 3 tablespoons|220 grams whipping (heavy) cream

• 3 tablespoons|45 grams whole milk

• 7 ¼ ounces|220 grams semisweet or bittersweet dark chocolate, chopped

• 1 ½ tablespoons|45 grams unsalted butter, at room temperature

Directions

  1. Heat the oven to 350°F. Line a sheet pan with a silicone baking mat or parchment paper and set an 8-inch (20-centimeter) cake ring in the pan.
  2. Coat the puffed rice: Put the puffed rice in a large bowl. Put the corn syrup in a small heatproof bowl and microwave for 30 seconds, then pour the warm corn syrup over the puffed rice. Sprinkle with the sugar, then mix with a spatula until the rice is evenly coated. (You may find that using your hands is easier).
  3. Shape the puffed rice: Transfer the puffed rice to the cake ring, pressing it into an even layer about ¼ inch (6 millimeters) thick. If you plan on using the caramelized puffed rice as a topping, separate it in clusters on a sheet pan.
  4. Bake the puffed rice for 10 to 15 minutes, until golden-brown and caramelized. Let the puffed rice cool completely in the cake ring. Unmold the puffed rice, then carefully peel away the silicone mat or parchment.
  5. Put the chocolate in a heatproof bowl. Microwave in 10-to-15 second intervals, stirring after each, until just melted -- don't let it get too hot. Line a sheet pan or an 8-inch (20-centimeter) cake pan with parchment paper. Place the disc of puffed rice in a large bowl. With your hands, break it into smaller pieces. Pour the melted chocolate over the puffed rice and fold with a spatula until coated.
  6. Spread the coated puffed rice over the prepared sheet pan or press it into the prepared cake pan. Refrigerate until firm, about 20 minutes. Gently unmold the puffed rice and remove the parchment. (Work quickly, or the chocolate will melt.)
  7. Make the peanut butter mousse: Combine the gelatin and cold water in a small bowl and stir with a spoon until the gelatin has dissolved. Put the milk in a medium saucepan and bring to a boil over medium heat. Remove from heat and keep warm.
  8. Make the custard: Whisk together the egg yolks and sugar in a large bowl until combined. While whisking, slowly pour in a little bit of the hot milk to temper the eggs and whisk until combined. Whisk in a bit more of the milk, then pour the tempered egg mixture into the saucepan with the remaining milk.
  9. Cook the custard over medium-low, gently stirring with a spatula, until thick enough to coat the back of the spatula, about 10 minutes. Remove from the heat. While the custard is still warm, add the peanut butter*, then the gelatin mixture, and stir until combined. Let cool completely, about 30 minutes, or refrigerate for 10 to 15 minutes.
  10. In a stand mixer fitted with the whisk attachment (or in a large bowl using a hand mixer or whisk), whip the cream on medium speed until it holds soft peaks, about 5 minutes. Slowly pour the custard into the whipped cream a little at a time, gently folding with a spatula until just combined.
  11. Make the dark chocolate ganache: Combine the cream and the milk in a small saucepan and bring to a boil over medium heat. Remove from the heat and keep warm.
  12. Place the chocolate in a large bowl. Slowly pour the cream mixture over the chocolate and whisk until the chocolate has melted and the mixture is smooth. Add the butter and whisk until fully incorporated. Let cool completely.
  13. Assemble the cake: *If your peanut butter is particularly thick, put it in a medium bowl, add a scoop of the custard, and stir with a spatula to loosen it, then add the peanut butter mixture to the saucepan with the remaining custard.