I am making a strawberry & chocolate cake both with strawberry mousse filling and wanted to cover it in ganache then in buttercream. My question is can I leave the cake out since I'm covering the cake in ganache and then buttercream, even though the filling is a mousse filling?
Things are to be stored at the temperature which the most perishable ingredient requires. In this case the mousse is the most perishable ingredient and most likely should be stored refrigerated. Therefore the cake should be stored refrigerated.
Why do you want to use ganache AND buttercream - they are both either used alone or as a layer under fondant? I would think that it would be a very rich, sickly combination together . In any event, mousse should always be kept in the fridge, or it will spoil/collapse.
what is in your mousse? To make most of my mousse filling, I use preserves and then mix with some buttercream, never had a problem with that sitting out for a while... If you buy some of those fillings, they are room temp safe as well..
If your mousse contains whipping cream then you need to refrigerate. I have let mousse filled cakes sit out during an even for around five hours with no problems but indoor events only. I would not leave it out overnight. If you want to make a mousse that doesn't need refrigeration then sub Bettercreme or Frostin pride in place of the whipping cream.
Thanks for the info, but decided to go with the raspberry sleeve filling instead.