Add butter to the bowl of a stand mixer fitted with a paddle attachment. Mix at medium speed for 2 to 3 minutes.
Scrape down the sides of the bowl and add powdered sugar.
Mix at medium for about 2 minutes, then add milk and vanilla extract. Continue to mix for about 2 additional minutes, or until light and fluffy. This will yield about 1 to 1 ½ cups of buttercream.
Notes
This recipe yields approximately 1 1/2 cups of buttercream. The nutrition label is for the full batch.