I am doing a cake for my cousins' daughters' wedding tomorrow.She wanted the marshmallow buttercream filling. I have my cakes leveled and filled already, but the filling is made of all butter and no shortening and now I am a little nervous about it holding up. I made my dam out of stiffened buttercream that has all shortening in it, just like the outer frosting will have. Do you think this will be okay, or am I asking for trouble? My car has air, and I am quite sure the reception hall will also. I just wanted to hear what some of you think before I continue to finish the cakes. Thanks in advance for any help I may get.

It should be fine, I use real buttercream INSIDE my cakes all the time, even in ones that go outside in hot weather but I chill my cakes so it takes a long time for the heat outside to reach the inside of the cake. If you're using weather resistant shortening based bc on the outside of the cake you should be fine. PLUS, it's going inside, in a/c? No problemo.

Thank you so much toptier for responding. I have gone ahead and started to ice the cakes, and I kept telling myself that there really shouldn't be a problem, but I was just still a little nervous, now I feel a lot better about my decision. Thanks again.