ok, I won’t say Amen, I respect everyone is not necessarily religious.
If you think the buttercream tastes too buttery add a bit more vanilla. It will make the icing taste sweeter. I have never had anyone tell me they liked sprinkles cupcake frosting (butter and confectioner’s sugar) better than mine in a side-by-side taste test. Sprinkles is supposed to be the last word in cupcakes here in southern California, but I can tell you that after we open Ella Vanilla, Sprinkles will be come an “also ran”! And it will all be thanks to Mousseline buttercream!