I have a recipe for strawberry buttercream filling that is just powdered sugar, finely chopped strawberries, and butter. Does this need refrigeration, or will the PS act as a preservative?
Sorry such a dumb question.
Powdered sugar acts as a preservative in American buttercream when the proportion of powdered sugar is great and the amount of liquid is very small.
To be on the safe side, I'd just refrigerate.