Google a recipe tjat calls for cooking milk and flour (yes cooking milk & flour) it's a VERY GOOD recipe.
Duncan Hines has a good butter cream frosting.
Have you tried Googling "American Buttercream" recipies? They're pretty much the same in terms of ingredients (powdered sugar, butter, milk, vanilla extract) and are really easy to make. Good luck!
The Wilton web site has recipes. So does their app (which doesn't work very well in Android).
Swiss meringue buttercream!! The best
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