Weigh or lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, baking powder, and salt, stirring with a whisk. Gradually add flour mixture to peanut butter mixture, beating until blended (batter will be thick). Spread batter evenly in a 13 x 9-inch metal baking pan coated with cooking spray.
Bake at 350°F for 26 to 28 minutes or until a wooden pick inserted in center comes out clean.
2/3 cup Semisweet Chocolate Chips
Place chocolate in the top of a double boiler set over slightly simmering water; melt chocolate chips, stirring until smooth. Spread chocolate evenly over top. Cool completely on a wire rack. Cut into bars.
Helpful Tips: 1. A combination of butter and canola oil lightens up the batter. 2. Spread a thin layer of chocolate on the bars to keep the recipe light.