01 -
Place peanut butter in a heat-safe bowl and microwave for 20-30 seconds until pourable but not hot. Line an 8-inch metal square pan with parchment paper, leaving an overhang. Spread peanut butter evenly in the pan and freeze for 1 hour or until solid. Use the parchment to remove the peanut butter sheet from the pan, and return it to the freezer while making the brownie batter.
02 -
Preheat oven to 350°F (175°C). Line the square pan again with parchment paper, leaving an overhang.
03 -
In a large microwave-safe bowl, combine butter and chocolate. Microwave in 30-second bursts, stirring each time, until melted and smooth. Add sugar and whisk vigorously until combined. Cool until just barely warm.
04 -
Add eggs, egg yolk, and vanilla extract to the butter mixture. Whisk for about 1 minute until very well combined.
05 -
Use a rubber spatula to mix in flour, cocoa powder, and salt until just combined.
06 -
Pour half the batter into the prepared pan and smooth out. Carefully place the frozen peanut butter sheet over the batter. Pour the remaining batter on top, spreading evenly to cover.
07 -
Bake for 30 minutes or until cooked through but slightly gooey in the center. Cool the brownies in the pan for 30 minutes. Remove from pan and cool for another 30 minutes before slicing and serving.
08 -
Store brownies in an airtight container at room temperature for up to 3 days or refrigerate for up to 5 days. Serving them chilled makes the brownies extra fudgy.