Use a fork or electric mixer (I use my KitchenAid with the paddle attachment) to cream the butter. Gradually work in the sugar, alternating with the cream and beating well after each addition. Stir in the vanilla. If the frosting is too thick to spread, add a little more cream, a teaspoon at a time. If it is too thin (which is unlikely), refrigerate; it will thicken as butter hardens.
Recipe by This Week for Dinner at https://thisweekfordinner.com/pink-elephant-on-parade-and-swiss-meringue-buttercream-frosting/