Ingredients
8 tbsp. unsalted butter
2 oz. good-quality unsweetened chocolate
4 oz. good-quality semisweet chocolate
c. all-purpose flour
1/2 tsp. baking powder
1/4 tsp. salt
3/4 c. granulated sugar
3 large eggs
2 tsp. pure vanilla extract
4 tbsp. unsalted butter
1/2 c. confectioners’ sugar
3/4 c. smooth peanut butter
1/4 tsp. salt
1/2 tsp. pure vanilla extract
Preparation
Step 1Preheat oven to 325 degrees F. Butter an 8-inch square baking pan and line with parchment, allowing a 2-inch overhang. Butter lining (not overhang).Step 2Make batter: Put butter and chocolates in a heatproof medium bowl set over a pan of simmering water; stir until melted. Let cool slightly. Whisk together flour, baking powder, and salt in a bowl.Step 3Whisk granulated sugar into chocolate mixture. Add eggs, and whisk until mixture is smooth. Stir in vanilla. Add flour mixture; stir until well incorporated.Step 4Make filling: Stir together butter, confectioners’ sugar, peanut butter, salt, and vanilla in a bowl until smooth.Step 5Pour one-third of batter into prepared pan; spread evenly with a rubber spatula. Drop dollops of peanut butter filling (about 1 tablespoon each) on top of batter, spacing about 1 inch apart. Drizzle remaining batter on top, and gently spread to fill pan. Drop dollops of remaining filling on top. Gently swirl peanut butter filling into batter with a butter knife, running the knife lengthwise and crosswise through layers.Step 6Bake until a cake tester inserted into brownies (avoid center and edges) comes out with a few crumbs but is not wet, about 45 minutes. Let cool slightly in pan, about 15 minutes. Lift out; let cool completely on a wire rack before cutting into squares. Brownies can be stored in an airtight container at room temperature up to 3 days.
