1/2 cup granulated sugar
1/2 cup packed brown sugar
1/4 cup butter or stick margarine, softened
2 large egg whites
1 teaspoon vanilla extract
1 1/4 cups all-purpose flour
1/2 teaspoon baking powder
1/4 teaspoon salt
1/2 cup butterscotch morsels (I used peanut butter and chocolate chips)
Preheat oven to 350°.
Beat sugars and butter at medium speed of a mixer until well-blended (about 4 minutes). Add egg whites and vanilla; beat well. Lightly spoon the flour into dry measuring cups, and level with a knife. Combine flour, baking powder, and salt; stir well with a whisk. Add flour mixture to sugar mixture; beat at low speed just until blended.
Spread batter evenly into an 8-inch square baking pan coated with cooking spray; sprinkle evenly with morsels. Bake at 350° for 28 minutes (I baked for 17-18 minutes, I recommend about 15 minutes) or until a wooden pick inserted in center comes out clean. Cool in pan on a wire rack.