The BEST, richest, and fluffiest Peanut Butter Frosting! I have made this Peanut Butter Buttercream recipe countless times, and it's a tried-and-true staple! You need this recipe in your life. If there's someone that knows Peanut Butter Frosting, it's me. I've made this Peanut Butter Frosting recipe countless times. I'm also a self-proclaimed peanut butter expert.