- 1 cup (5 ounces/140 grams) salted peanuts
- 1 large egg white
- ¼ cup (1 ounce/30 grams) white sesame seeds
- 1/3 cup (2¼ ounces/65 grams) granulated sugar
- 1/3 cup plus 1 tablespoon (3 fl ounces/90 ml) heavy cream
- 6 tablespoons (3¼ ounces/90 grams) creamy peanut butter
- 5 ounces (140 grams) white chocolate, coarsely chopped
- 1 recipe (8-inch square) favorite buttermilk cake
- Bake the cake as directed, and let cool completely on a wire rack.
- Before baking the Peanut-Sesame Crunch:
- Center a rack in the oven and preheat the oven to 350 degrees F. Have ready a large baking sheet, preferably lined with a silicone mat.
- To make the Peanut-Sesame Crunch:
- Coarsely chop the peanuts on a cutting board to yield 1 cup. Place the egg white in a medium bowl and add the peanuts. Sprinkle the sesame seeds and sugar over the nuts and toss with a rubber spatula to coat the nuts. Spread the coated nuts in a thin layer on the prepared baking sheet.
- Bake the nuts for about 35 minutes, tossing with a rubber spatula every 5 to 7 minutes to redistribute them so they dry and toast evenly. At first the mixture will resemble a syrup with nuts, but as it bakes, the sugar will dissolve and the mixture will caramelize and become crisp and golden. Transfer the pan to a wire rack and let cool completely, then store in a sturdy airtight container at room temperature for up to 10 days. If desired, crush with a rolling pin before sprinkling over the cake (or over cookies or pies). You should have 1¾ cups.
- To make the Peanut Butter-White Chocolate Ganacbe:
- In a small, heavy saucepan, heat the cream and peanut butter over medium heat and whisk to combine the ingredients. Half fill a saucepan with warm water (95 to 110 degrees F).
- Put the white chocolate in a bowl and place it over (but not touching) the warm water. Allow to sit just until some of the white chocolate on the bottom of the bowl is liquid. Remove the bowl of chocolate and stir with a rubber spatula just until most of the chocolate is melted (a few tiny pieces of chocolate might remain).
- Stir the slightly warm peanut butter mixture into the white chocolate until smooth. Take care not to overmix or the ganache might separate. Set aside at room temperature until needed. The mixture will thicken as it cools. You should have about 1¼ cups.
- To assemble the cake:
- Cut an 8-inch cardboard square, and cover one side of the square with aluminum foil. Place the cake, right side up, on a cutting board. Using a 12-inch serrated knife, split the cake horizontally into 3 layers, each 5/8 inch thick
- Place the bottom cake layer on the foil-covered square. Spread about half of the ganache evenly over the layer and center the second cake layer on top. Spread all but 2 tablespoons of the remaining ganache on top. Top with the last cake layer and spread the remaining 2 tablespoons ganache on top in a thin layer just to cover the surface. Refrigerate just to firm the frosting, 15 to 30 minutes.
- Remove from the refrigerator and, using the serrated knife and a sawing motion, trim about ¼ inch off of all 4 sides of the cake, exposing the peanut butter filling. Scatter the Peanut-Sesame Crunch over the top of the cake.
- Transfer the dessert to a cake stand or large cake plate. Serve at room temperature, cutting square portions with a serrated knife.