Recipe Source: Betty Crocker
Serves: Makes a 9x13 pan
1/2 cup butter, softened (not too soft!)
1/2 cup creamy peanut butter
2 cups powdered sugar
2 teaspoons milk
1. Heat oven to 350°F. Grease bottom only of 13x9-inch pan with cooking spray or shortening. (For easier cutting, line pan with foil, then grease foil on bottom only of pan.)
3. In medium bowl, beat filling ingredients with electric mixer on medium speed until smooth. The mixture will be very thick. Spread mixture evenly over brownie base. I find the easiest way to do this is to use my hands and pat it down.