I made a caramel buttercream with snicker pieces to fill a chocolate cake and was wondering if you all could help me out with a quick question? I know my buttercream by itself does not have to be refrigerated BUT I added a small amount of canned La Lechea (Nestle's canned Dulce de leche) and the can says refrigerate after opening. Now my question is Do I have to refrigerate it since it was whipped up with buttercream? Doesn't the sugar in the buttercream act as a preservative?? Im still new to this!
Thanks!!!

I've used the canned dulce de leche as a filling on its own, not mixed with anything, and left the cake at room temperate with out any problems at all.