In a large bowl or the bowl of a stand mixer, beat 1 1/2 cups of butter and 1 cup of creamy peanut butter on a medium speed for 30 seconds with a paddle attachment or hand mixer until smooth.
Mix in 1 tsp vanilla extract and 1/2 tsp salt on a low speed until the ingredients are incorporated.
Gradually mix in 7 cups of powdered sugar and 1/3 cup of heavy cream on a low speed. Scrape the sides and bottom of the bowl as needed with a rubber spatula.
Mix on low until desired consistency for the frosting is reached. If the frosting seems too thick, add in additional cream (1 Tbsp at a time). If the frosting seems too thin, add in more powdered sugar (1/4 cup at a time).
If you want to color this buttercream, add in the gel food coloring once the frosting is fully made. Beat on low until it reaches the desired colored. Cover the frosting with plastic wrap to prevent crusting until you're ready to use it.
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Notes
How Much Frosting Does This Recipe Make?
This recipe makes about 7 cups of frosting. If needed, this recipe can be halved or doubled. A double batch can be made in a 5 qt KitchenAid mixing bowl.I usually make one batch to frost three dozen cupcakes with large swirls or to fill and frost a 7- or 8-inch layer cake.
Tips for Making the Best Peanut Butter Buttercream Frosting
Make sure the butter is at room temperature before making your frosting.
If your powdered sugar contains cornstarch (most brands in the US do) there's no need to sift the powdered sugar.
Make sure your buttercream has the right consistency! This will make it much easier to use.
If you are making this frosting for a cake, mix the buttercream on the lowest speed at the end of the process for a couple minutes to get out any extra air that might have been incorporated during the mixing process.
Making This Peanut Butter Buttercream in Advance and Storage Tips
This buttercream can sit out at room temperature for up to 2 days or be stored in an airtight container in the fridge for up to a month. This frosting can also be stored in the freezer for up to 3 months! Just be sure to give it a good stir once it thaws to make it nice and smooth again.A frosted cake can last in the fridge for a week, or in the freezer for a month. The buttercream locks in the moisture and keeps the cake fresh and delicious!