Instructions

• Preheat the oven to 350°F. Line an 8x8-inch baking pan with foil or parchment and spray the liner with nonstick cooking spray; set the pan aside.
• In a large microwave-safe bowl combine 4 ounces bittersweet chocolate (roughly chopped) and ¾ cup unsalted butter (cut into cubes). Microwave at medium (50%) power, stirring every 30 seconds, until the chocolate and butter are melted and the mixture is smooth. (Alternatively, melt over a double boiler.)
• Whisk the chocolate mixture briefly to smooth, then add 1 cup granulated sugar, 3 large eggs (slightly beaten), 1 teaspoon pure vanilla extract, and ¼ teaspoon salt. Whisk to combine.
• Using a rubber spatula, fold 1 cup all-purpose flour into the chocolate mixture until just combined. Do not overmix.
• Spread half of the brownie batter evenly in the prepared 8x8 pan. Arrange 9 peanut butter cups evenly over the batter. Spoon or spread the remaining batter over the peanut butter cups and smooth the top. Bake in the preheated oven for 30 minutes, or until set. Transfer the pan to a cooling rack and cool completely in the pan.
• When the brownie slab is completely cool, lift it from the pan using the foil or parchment and transfer to a cutting board. Use a small glass or round biscuit cutter to cut 8 to 9 circular brownie shapes. Slice each brownie circle horizontally through its center to make two thinner circular brownie layers (you will have 16–18 thin rounds). Keep them covered until ready to assemble.
• Make the peanut butter mousse: in the bowl of a stand mixer fitted with the whisk attachment or in a large bowl with an electric mixer, beat 4 ounces cream cheese (softened), ½ cup creamy peanut butter, ½ cup plus 1 tablespoon confectioners’ sugar, ½ teaspoon pure vanilla extract, and 2–3 tablespoons heavy cream until the mixture is smooth and fluffy, about 3 minutes.
• Make the ganache: place 4 ounces bittersweet chocolate (roughly chopped) in a medium bowl. In a medium saucepan over medium heat bring 6 ounces heavy cream to a simmer, then immediately remove from the heat. Pour the hot cream over the chopped chocolate and let sit 3–5 minutes. Whisk until smooth. Allow the ganache to cool at room temperature 10–15 minutes, until slightly thickened but still pourable.
• Assemble the parfaits (makes 8–9 servings): in each trifle dish or small glass place one thin brownie round on the bottom. Pipe or spoon an even layer of peanut butter mousse over the brownie. Top with a second thin brownie round, spoon a layer of ganache over it, and finish with a layer of whipped cream. If desired, garnish with additional whipped cream and chopped peanut cutter cups. Refrigerate the assembled parfaits for a few hours to set, or serve immediately.