This type of frosting does require refrigeration, and should not be used when the cake will be left in a climate above room temperature for more than an hour.
- The Best Cake Icing Recipe
5 Sticks of unsalted regular butter
5 cups of powdered sugar
1/4 teaspoon of salt
1 Tablespoon + 1 teaspoon of vanilla extract
1/4 cup of heavy cream
With electric mixer, whip softened butter, add sugar, salt and continue whipping.
Finally add cream and extract, and whip till fluffy. (about 5 min.)