Pre-heat oven to 350°F degrees. Coat a 13 x 9 x 2 baking pan with cooking spray. Beat butter and peanut butter in a large mixing bow. Add sugars, beating well.
Pre-heat oven to 350°F degrees. Coat a 13 x 9 x 2 baking pan with cooking spray. Beat butter and peanut butter in a large mixing bow. Add sugars, beating well.