Can you freeze chocolate mousse and for how long?
I've never tried it. I'm sure it would affect the texture of the mousse, but I don't know how adversely. If you do try it, please let us know if you were happy with it after you thawed it out.
In the "French Chef" Cookbook, Julia Child has a recipe for chocolate mousse w/butter & eggs that she specifically says can be frozen. Later in the book, she has a recipe for a frozen mousse containing egg yolks, milk & cream. Her instructions for freezing that recipe are: "The mousse must be frozen at zero degrees or it will not take properly. Sufficiently frozen, it will hold its shape & will cut like cream cheese. You may hold a mousse at zero degrees for several weeks at least". In a separate part of the book she adds that whipped cream can be formed into fancy shapes & frozen on waxed paper to be available whenever you need them. So it seems you're okay to freeze a mousse, although it may not be QUITE as airy later; I'm sure it will still be delicious. Bon Appetit!
A frozen mousse is different than a "regular" chocolate mousse. If freezing it is important to you, you need to choose a recipe that is designed to be frozen. The recipe I make for Chocolate Mousse would be wrecked by freezing.
Julia's recipe for Chocolate Mousse can be frozen, according to the cookbook. With regard to her "frozen mousse", she notes that there are two types: one w/sugar syrup & cream the other w/custard & cream. Both of her recipes that I referenced are "cooked" first.
I don't know what type of recipe ELCookie uses, but she can look up Julia's instructions to confirm.
Techinically wouldn't a frozen mousse just be a semi freddo? So maybe just make a semi freddo?
I don't know if this is 'technically' true, but it is very close. I've made a 'Frozen Lemon Mousse' that for all intents is a lemon semi freddo. We often do chocolate semifreddo for Christmas dinner - made in a loaf pan, it can be served in slices, and layered with fruit or amaretti crumbs or shaved chocolate, or whatever you like - double the fun.