Covering buttercream with ganache
I am attempting to copy the My Downfall (tm) cake from the CakeLove website:
I just frosted my 3-layer chocolate cake with swiss buttercream (meringue whipped with sugar syrup, then add the butter). I put a skim/crumb coat all over it and just stuck it in the freezer. I want to then coat it with ganache. Of course, I'll let the ganache cool before pouring it over, but my questions are: How cool should it be to (a) prevent melting of the buttercream but yet (b) drip down the sides sufficiently to coat it without it seizing upon hitting the cold buttercream.
This is for my husband's 39th birthday and based upon the cake scraps and leftover frosting, it is going to be one heck of a cake.
I'm using the King Arthur Flour's Baking Companion recipe for Devil's Food Cake and Gale Gand's recipe for basic Vanilla Buttercream, if anyone is interested. I'm just going to use a basic ganache (cream, dark chocolate, butter) recipe, but if anyone has a better-suited ganache recipe, please post it!
Well, I made a double-batch of ganache and only needed half. Oh what a shame to have leftover ganache! ;-) Anyway, it covered the cake perfectly, without any melting. I cooled the ganache to just about room temp. I did one base coat and another coat over that. Now, I just have to wait until after dinner.....
I would try to do two coats with the ganache if at all possible. In my experience baking professionally, we almost always did two pours over a crumb coat: one thin one to cover the crumb coat and a second one to smooth the cake (and put on more ganache for a real coating) since the first pour usually yields some streaks and a couple of uncovered patches here and there. I would have the ganache pretty liquid the first time and then let it thicken a bit for the second pour.
If you can't do two pours for lack of time or ganache (we had the luxury of a vat of it and big drip racks -- wish I had these now as a home baker), I would let the ganache cool to the consistency of very very thick heavy cream. If the cake is really frozen, a little melting of the B.C. shouldn't be a problem. Best wishes!