1 ½ cups semisweet chocolate chip (260 g), divided
1 ½ cups granulated sugar (300 g)
¾ cup brown sugar (150 g)
1 tablespoon vanilla extract
1 teaspoon kosher salt
3 large eggs, room temperature
1 ¼ cups all purpose flour (155 g)
⅓ cup dark cocoa powder (35 g)
Peanut Butter Filling
2 cups powdered sugar (220 g)
1 cup peanut butter (240 g)
1 stick unsalted butter, melted
1 cup crispy rice cereal (125 g)
8 oz milk chocolate chips (225 g)
¾ cup heavy cream (180 mL), hot
flaky sea salt, for garnish
How to Make It
Make the brownies: Preheat the oven to 350°F (180°C). Line a 9-inch (23-cm) square baking pan with parchment paper and grease with nonstick spray.
Add the butter and 1 cup of the chocolate chips to a large microwave-safe bowl. Microwave for 1½ minutes, then let sit for 3 minutes before whisking until smooth. Add the granulated and brown sugars, vanilla, and salt. Whisk to combine. Whisk in the eggs until fully incorporated.
Sift the flour and cocoa powder into the bowl and fold to combine with a spatula. Add the remaining ½ cup chocolate chips and fold to incorporate.
Pour batter into the prepared pan and bake for 35–40 minutes, until a toothpick inserted in the center comes out with a few moist crumbs attached. Let cool completely.
Make the peanut butter filling: In a medium bowl, use a rubber spatula to mix together the powdered sugar and peanut butter until crumbly. Add the melted butter and mix with an electric hand mixer until smooth.
Scoop the peanut butter filling on top of the cooled brownies and use offset spatula to spread in an even layer. Sprinkle the crispy rice cereal on top. Freeze for 30 minutes.
Make the chocolate ganache: Add the chocolate chips to a medium heatproof bowl. Pour the hot cream over the chocolate chips and whisk until the chips are melted and the ganache is smooth.
Pour the ganache over the peanut butter filling. Use offset spatula to spread in an even layer. Garnish with flaky salt, if desired.
Return the brownies to the freezer until the ganache sets, about 15 minutes.