01 -
In a large mixing bowl, use a hand mixer or stand mixer to beat softened butter until light and fluffy, 2 to 3 minutes.
02 -
Add in vanilla extract and mix until combined and smooth.
03 -
Add in cocoa powder (if making chocolate buttercream), and powdered sugar 1 cup at a time, mixing in between additions until smooth.
04 -
After adding the first 2 cups, add in milk and whip until smooth before adding the final cup of powdered sugar.
05 -
Frost immediately or store covered in an airtight container.