Originally Posted by purple.alien.giraffe
The buttercream frosting recipes I've seen use butter, powdered sugar, a small amount of whipping cream or milk, and whatever flavoring. Maybe adding whipping cream or milk to the butter being turned into savory frosting would help?
That's 1 cup of butter to 3-4 cups of powdered sugar...the bulk of the buttercream is powdered sugar...there will have to be something in the savory frosting to add that bulk from the missing ingredient and I don't think that much cornstarch would taste very good.
Easy check, there is a 1:3-4 ratio to try out, try with a tablespoon of butter and go from there, taste and determine if it tastes good.