I am doing a fondant cake which will have whipped cream as a filling. I know that it is important to dam cakes with soft fillings but I've only ever done it with buttercream. The cake I'm doing will be covered in ganache. Can I use the same ganache that I'm covering the cake with to make the dam? I'm just worried that the filling is going to ooze out of the cake. Thanks.
Are you covering it with the ganache as a glaze? If you let it cool and thicken overnight, at room temp, it should be fine to use as a dam. You could always whip it too, to get it to more of a frosting consistency for a dam. I did do a cake just last night with whipped cream as one of the fillings, but I didn't use a dam. I only use a dam for things such as strawberry filling. I have found that especially with ganache I can get away without doing one, which I prefer.
what is a dam and how do you do it?
A dam is frosting piped around the edge of your cake layers as you are assembling to contain your filling, so it doesn't leak out the sides.
I also don't do a dam when covering the cake in ganache. I find nothing gets thru my ganache but if you are worried, you could do one.