In the bowl of a stand mixer fitted with the paddle attachment, beat the butter on medium-high speed until smooth and slightly lightened.
Reduce the mixer speed to low and add the powdered sugar ½ cup at a time, allowing it to mix in completely before adding the next batch.
Once all the sugar has been incorporated, add the peppermint extract and mix on medium speed until smooth.
Switch to the whisk attachment. Add heavy cream and whisk on high until light, fluffy, and white.
Video
Notes
Yield –About 3 cups (enough to frost 24 cupcakes or one 9-inch layer cake)Flavor Tips – Start with 1/4 teaspoon if you're worried about the peppermint being too strong, you can always add more!Storage –Store in an airtight container in the fridge for up to 1 month or in the freezer for up to 3 months. Bring to room temperature and recondition before using.