Place the softened vegan butter into a large mixing bowl. Using a hand mixer or a sturdy whisk, beat the butter until it's smooth and creamy.
Add the vegan cream cheese to the bowl with the butter. Continue to beat until well combined and creamy. If you're using a stand mixer, make sure to scrape down the sides.
Gradually add the sifted powdered sugar 1/2 cup at a time. Check the consistency after 3 cups; your frosting should be thick and spreadable. If it's too thin or not sweet enough, continue to add more powdered sugar, one cup at a time.