This is VERY LIGHT & FLUFFY, and can be used as a filling and not just a frosting. I have even used it for "peanut butter pie" filling:

1 C. creamy peanut butter
8 oz. cream cheese, softened
8 pz. Cool Whip, thawed
1/3 C. powdered sugar

Beat the peanut butter with the cream cheese til combined and smooth. Add the powdered sugar. Fold in the Cool Whip, and it's ready in a "jiffy" -- (tee, hee!)