Chocolate Peanut Butter Layer Brownies
2 ounces unsweetened chocolate, chopped
1 stick (½ cup) unsalted butter, softened
1¼ cups sugar
3 large eggs
1 teaspoon vanilla
2/3 cup all-purpose flour
½ teaspoon baking powder
½ teaspoon salt
½ cup chunky peanut butter
3 ounces fine-quality bittersweet chocolate (not unsweetened), chopped fine, or ½ cup semisweet chocolate chips
Preheat oven to 350 degrees and butter and flour a 9-inch square baking pan, knocking out excess flour. In a double boiler or metal bowl set over a saucepan of barely simmering water, melt chocolate, stirring until smooth and remove top of double boiler or bowl from heat. Cool chocolate to room temperature.
In a large bowl with an electric mixer, beat butter and sugar until light and fluffy and beat in eggs, 1 at a time, beating well after each addition; add vanilla. Into a small bowl sift together flour, baking powder and salt and beat into butter mixture just until blended well. Divide batter between 2 bowls. Whisk peanut butter into batter in 1 bowl. Whisk melted chocolate into batter in other bowl and stir in chopped chocolate or chocolate chips.
Spread peanut-butter batter evenly in pan. Drop chocolate batter by large spoonfuls onto peanut-butter batter and spread carefully to form an even layer. Bake brownies in middle of oven 35 to 40 minutes, or until a tester comes out with crumbs adhering to it. Cool brownies completely in pan on a rack before cutting into 16 squares. Brownies keep, layered between sheets of waxed paper in an airtight container at cool room temperature, 5 days.
From Sara Moulton