This homemade peanut butter frosting recipe is amazing--it balances flavor against sweetness well, and the texture is perfect: creamy, fluffy, not oily at all.
Just a word of warning: Do not use margarine; use butter. Butter will give you beautiful, fluffy icing (and that's what you want).
FLUFFY PEANUT BUTTER FROSTING
1-1/4 cups homemade peanut butter, room temperature
1/2 cup butter, room temperature
1-1/2 cups powdered sugar
2 to 3 TBS heavy cream, room temperature
1/2 tsp pure vanilla extract
Beat the peanut butter and butter for several minutes until really creamy.
Gradually add the powdered sugar and beat well after each addition. Add the cream and vanilla extract; beat for 3 to 4 minutes.