When I found this recipe I went right into the kitchen and made it. No I didn't have a cake baked. Who needs cake? Frosting is like raw cookie dough - it can stand alone as a treat. Don't worry, I baked one the next day.
I really don't use a recipe I just use butter, about 1 1/2 cups, a bit of vanilla and then I add powdered sugar until it's stiff and milk to thin it out a little.
Here's a butter-cream recipe from Wilton:
1/2 cup vegetable shortening (I use coconut oil instead if I don't want to use all my butter)
1/2 cup butter
1 teaspoon vanilla
4 cups powdered sugar
2 Tablespoons milk
Cream butter and shortening with electric mixer. Add vanilla, gradually add sugar, one cup at a time, beating well on medium speed. Scrape sides and bottom of bowl often. When all sugar has been mixed in, icing will appear dry. Add milk and beat at medium speed until light and fluffy. Keep bowl covered with a damp cloth until ready to use. This icing can be stored for 2 weeks and for months in the freezer. Makes 3 cups.