What is the difference between chocolate truffle, ganache, and chocolate mousse cake fillings? How do I know which to choose for my cake?
This is a great question, partly because it’s a question, and I love answering questions, but also partly because it illustrates an issue of semantics. And here we go.
Chocolate Cake Fillings
Ganache, truffle, mousse.
Technically, these two chocolate cake fillings, ganache and truffle, are the same thing. Traditional, authentic truffles are nothing more than ganache rolled into little lopsided balls and dusted with cocoa powder. They look like the little fungus truffles, hence the name.
So, there is really no difference at all between ganache and truffle filling.
Having said that, nothing is ever as simple as that. There are different ratios of chocolate to cream to make different consistencies of ganache. Ganache made for truffle fillings is, more or less, 2 parts chocolate to 1 part liquid (predominantly cream but also could include a flavored liquid such as wine or coffee or a liqueur). A ganache made with equal parts chocolate and cream (1:1) will not set up as firmly as a classic truffle filling and is best used as a cake glaze. Make a ganache with 1:2 chocolate to cream, chill it, and then you can whip it. This gives you a more-or-less instant chocolate mousse that you can use as a filling and a frosting. You can even use a 1:1 ganache “straight up” for filling and then whip it for frosting. Or vice versa. It’s very versa versa versatile.
And see there. It didn’t take long for the third term to crop up: mousse.
Mousse means “foam” in French, so pretty much anything foamy or lightened with whipped egg whites (very foamy stuff) is a mousse.
What I think of when someone says “chocolate mousse” is the basic French kind: melted chocolate (and maybe some butter), egg yolks whisked in followed by whipped egg whites (hello foam) and whipped cream (hello, more foam). But it’s possible to make an even simpler mousse with just melted chocolate folded together with cream whipped to medium peaks. Hey, wait. Chocolate + cream = ganache or truffle filling. And it also equals mousse when you whip the cream first. Magic!
So, in more complete answer to the first part of Elise’s question, there is very little difference in ingredients among truffle, ganache and mousse fillings. There may be a marked difference in texture, certainly with the mousse, but also if you whip the ganache.
If you need a primer on making ganache, I just happen to have a video for you.