This fluffy Peanut Butter Frosting is the perfect topper for cakes and cupcakes! The one-bowl recipe takes just a few simple ingredients and is ready in under 10 minutes.
In a large bowl using a hand mixer or the bowl of a stand mixer fitter with the paddle attachment, beat the butter and peanut butter together on medium-high speed until smooth and fluffy, 2 to 3 minutes. Beat in the vanilla and salt until just combined.
With the mixer on low speed, gradually add the sugar. Once incorporated, increase the speed to high, and beat until fluffy, about 1 minute. If the frosting feels too stiff or grainy at all, beat in a little bit of milk until smooth and spreadable.
Pipe or spread the frosting over cooled cakes or cupcakes. This recipe will generously frost 12 cupcakes or modestly frost 24 cupcakes, one 9x13” sheet cake, or a 2-layer cake.
Notes
Stick to smooth peanut butter. If you plan to pipe this recipe instead of spreading it, I recommend using a smooth peanut butter for the best texture. Chunky peanut butter can work for textured and spreadable frosting, but smooth with give you the best light and fluffy texture.
Make sure your butter is actually soft. A softer butter will incorporate into soft peanut butter much more easily and smoothly than a butter that is still somewhat firm. If the butter is easily spreadable, then it is soft enough. If the butter is still firm at room temperature, pop it in the microwave for 3 to 5 seconds. Be sure to not melt it though!
Slowly mix in the sugar. Make sure the electric mixer is on low speed before gradually adding the powdered sugar – you want to give it time to slowly incorporate. Once it is all combined, increase the speed and mix on high for only about 1 minute, or just until peaks form. This will create the fluffiest texture.
Optional variations. Jazz up the recipe by using flavored creamy peanut butter like honey-roasted or chocolate. Additionally, if you prefer a stiffer frosting, increase the powdered sugar in the recipe to 3½ - 4 cups.