The peanut butter buttercream Icing by Wilton is a well-rated peanut butter frosting recipe. As of 2015, the recipe has a rating of 4 1/2 out of 5 stars, with more than 80 votes.
To prepare the recipe, combine 1/3 cup solid vegetable shortening and 1/3 cup butter in a mixing bowl, and cream them with an electric mixer. With the mixer on medium speed, add 3/4 cup of peanut butter and 1 teaspoon pure vanilla extract before gradually adding 4 cups of sifted confectioners' sugar 1 cup at a time. Scrape the sides of the bowl frequently while mixing. Once all the sugar has been added, add 4 to 6 tablespoons of milk to the mixture 1 tablespoon at a time while beating the icing on medium speed until it is light and fluffy.
This recipe yields approximately 3 cups of peanut butter icing. Keep the icing in the refrigerator covered by a damp cloth when not in use. If not used immediately, the icing can last up to 2 weeks in the fridge when stored in an airtight container. Whip the icing again before spreading it on chocolate cupcakes, a chocolate cake, chocolate brownies or your dessert of choice. For a unique flavor variation, try adding some cooled espresso or melted baker's chocolate to the icing.