Cream the Earth Balance in the bowl of your mixer fitted with the paddle attachment for about 1 minute, scraping down the bowl after 30 seconds to ensure even creaming. Next, add sifted powdered sugar, 1 cup at a time, letting the sugar incorporate before adding the next cup.
Once all the powdered sugar is in the bowl, mix on medium speed for about 2-3 minutes, stopping every minute or so to scrape the bowl down to ensure that all of your buttercream is incorporating air evenly.
After about 3 minutes, your buttercream will still be pretty thick. Turn the mixer to low speed and add the vanilla extract 1 teaspoon at a time, fully incorporating the first before adding the second. Your buttercream should start to noticably get lighter here. If you have achieved your desired buttercream consistency, stop here.
If you want your buttercream to be a little lighter, add your plant milk of choice 1 tablespoon at a time, incorporating completely before adding another tablespoon, until you achieve your desired consistency.
And now you’re ready to frost away!