I’m in the process of planning a winter wonderland/snowman birthday cake for my son’s and my daughter’s upcoming birthdays.  I’m envisioning a snow scene with a white buttercream (likely IMBC with white chocolate) and meringue snowman, trees, and a blue candy lake (melting blue candies).  Does anyone have experience with meringues on buttercream?  The cake will likely need refrigeration, but I’m hoping that after it’s at room temp I can apply the meringue decorations and they will hold up for a few hours. 

I know meringues don’t do well in humid environments, but if anyone has had experience with this, I’d appreciate any suggestions.  I will likely attempt a few tests, but even tests are not totally reliable unless of the same magnitude as the end product!

Your cake sounds lovely….I’m sure your children will love it!

My experience isn’t with meringue and buttercream, but with meringue and whipped chocolate ganache. I made a Buche de Noel this past Christmas and garnished with mushrooms made from TCB recipe, figure piping variation. Some mushrooms were embedded into the frosting on the log, the others were attached to the cake board with some of the ganache.

I had the same concern as you so I decorated the cake in a cool, dry room ~6 hours before serving and refrigerated for about 4 of those hours. The mushrooms stayed crisp. In fact, they were still crisp the next day. (The leftovers were refrigerated again overnight). I didn’t allow the cake into my warm, humid kitchen where all of the cooking was taking place. I noticed that the spare mushrooms that remained in the kitchen became sticky.

I think as long as you avoid exposing the meringues to a humid environment, they will be fine for a few hours.

Excellent, Sophia!  I do hope it works—the cake itself will be fine at room temperature for at least a day, but since it will be made in advance (possibly frozen)—I want to ensure the meringue doesn’t get soggy from condensation.