1 cup (2 sticks) unsalted butter (don't microwave to soften, let it sit out, it will affect the consistency if it's too hard or too runny)
4 cups powdered sugar (sifted, makes the frosting smoother)
1/4 tsp salt
1 TBSP vanilla extract
2 to 4 TBSP milk
Beat butter for a few minutes on medium speed. Add three cups of powdered sugar and see what the consistency is like, if it isn't thick enough add the last cup of powdered sugar. (I used 4 cups because I wanted it thick to decorate cupcakes.) Have the speed on low while mixing in the powdered sugar so it doesn't make a mess. Next add the vanilla, salt and 2 TBSP of milk. If the frosting is too thick add more milk a tablespoon at a time. I only used 2 TBSP because I wanted mine thick.
This is a simple buttercream recipe but it tastes really good! Make sure to use unsalted butter and sift your powdered sugar or the consistency won't be right. I found this recipe at savory sweet life dot com.