Place sugar, butter, peanut butter and eggs in a mixing bowl and mix up with an electric mixer until well combined and smooth.
Mix self-rising flour with baking soda.
Add flour to wet mixture alternately with the buttermilk.
Bake in three layer cake pans at 350 for about 35 minutes.
Allow to cool ten minutes in pan before turning out to cool completely.
For the Frosting: Combine peanut butter, cream cheese, and powdered sugar with two tablespoon of milk. You may need to add an extra tablespoon or two of milk if the mixture is too thick. Or, if the mixture becomes too runny for your tastes, add extra powdered sugar.
Beat with an electric Mixer until smooth and creamy.