Beat first 3 ingredients at medium speed with an electric mixer until creamy.
Gradually add powdered sugar alternately with 3 Tbsp. milk, 1 Tbsp. at a time, beating at low speed until blended and smooth after each addition. Beat in up to 2 Tbsp. additional milk for desired consistency.
Recipe is a keeper, and a great "base" for making flavored buttercreams (I make a strawberry one, and a blackberry one by adding a cooked down, strained fruit puree). This recipe makes MORE than enough for 24 regular cupcakes.
Fantastic recipe, easy to work with, very tasty. You can make your own vanilla bean paste by splitting 2 beans to within 1/4" of the ends and roasting in a low-temp oven until dry. Then grind them in a spice mill and add a tablespoon (more or less) of corn syrup until you achieve a slightly thin paste consistency.