Peanut Butter Filling

1/4 cup butter, softened
@ 1/2 cup creamy peanut butter
1/4 cup evaporated milk (I used this because I had some sitting in my fridge. Feel free to substitute an alternative dairy liquid, as long as it's creamy.)
1 tsp. vanilla extract
2 cups confectioners' sugar
@ one additional tablespoon evaporated milk

Cream butter and peanut butter together, then mix in the milk and vanilla. Beat in the confectioners' sugar, beating until creamy, and add additional milk as needed for the proper spreading consistency.