I don't know where my Aunts got this recipe, but this is taken from the handwritten index card given to me by my late Aunt Doll. She would often use this on a layered white cake and fling liberal amounts of sweetened shredded coconut on the surface after spreading it on the outside. I like it as it is. Sometimes all you need do is let butter, sugar, and cream speak for itself... with a little help from vanilla.
Recipe posted by JonMc