1 With An Electric Mixer, Mix The Butter And Cream Cheese Together, About 3 Minutes On Medium Speed Until Very Smooth. Scrape Down The Sides And Bottom Of The Bowl To Ensure Even Mixing. 2 Add The Vanilla Extract And Mix. Slowly Add The Powdered Sugar. Keep Adding Until You Get To Desired Sweetness And Thickness. 3 Either Spread On With A Blunt Knife Or Spatula, Or Spoon Into A Piping Bag To Decorate Your Cake Or Cupcake.