This recipe comes from the back of a package of Reese's peanut butter chips and it's also available on the website.
1/2 cup (1 stick) butter or margarine, softened
1/4 cup REESE'S Creamy Peanut Butter
1 cup granulated sugar
1 cup packed light brown sugar
1 teaspoon vanilla extract
2 cups all-purpose flour
2 teaspoons baking powder
1/4 teaspoon salt
1-2/3 cups (10-oz. pkg.) REESE'S Peanut Butter Chips
1/2 cup HERSHEY'S Syrup
Heat oven to 350°F. Grease 13x9x2-inch baking pan.
Beat butter and peanut butter in large bowl. Add granulated sugar and brown sugar; beat well. Add eggs, one at a time, beating well after each addition. Blend in vanilla.
Stir together flour, baking powder and salt; mix into peanut butter mixture, blending well. Stir in peanut butter chips. Spread about three quarters of batter in prepared pan; spoon syrup over top, be careful not to go all the way to the edge, stay within about 1/4 in of the edge. Carefully top with remaining batter; swirl with metal spatula or knife for marbled effect.
Bake 35 to 40 minutes or until lightly browned. Cool completely in pan on wire rack. Cut into squares. About 36 brownies.