Beat cream cheese and butter at medium speed with an electric mixer until creamy. Add powdered sugar alternately with buttermilk, beating at low speed until blended after each addition. Add vanilla, beating until blended.
Not recommended unless you thoroughly enjoy the sourness of buttermilk and have 48+ cupcakes to frost! The 1/3 cup of buttermilk is way too much and overtakes the other ingredients. The 8 oz. block of cream cheese has enough sourness to offer if that's your preference. I ended up adding (out of necessity) an additional 8 ounces of confectioner's sugar to only half the mix (threw away the other half as I had ruined it by tossing in coconut in a half-hearted attempt to offset the sour flavor). After adding the additional sugar, however, I achieved a pretty balanced mix. When I frosted my white cupcakes (also made with buttermilk, but with much better results), I topped them with toasted coconut, which produced a gourmet flair, if I do say so myself! To avoid waste, cut the recipe in half. Most importantly, however, reduce the buttermilk to around 1/5 c. or delete altogether if it's all the same to you. BTW, consistency=soft. Additional sugar also needed to thicken.