9 tablespoons butter, softened
1/4 cup creamy peanut butter
1/2 cup milk
1 1/2 teaspoons vanilla extract
5 1/2 cups powdered sugar
Beat butter and peanut butter in a large bowl at medium speed with an electric mixer until blended. Combine milk and vanilla. Gradually add sugar and vanilla milk, 1 tablespoon at a time, beating until spreading consistency.