That’s a good question — thanks very much to reader Steve T. (who’s really putting me on the spot here). It’s a good question because the names “torte” and “gâteau” are greatly abused in America. Too often one finds recipes in books or magazines for items that are really layer cakes, but because they have a few imported ingredients in them (or the author simply wanted to sound sophisticated) are given these exotic-sounding labels. So what exactly are the differences? There’s not much that I can find written on the subject, but what they hey, let’s give it a try.
First the similarities: they’re all sweet, all have a base of wheat flour (and egg and butter) cake and all have layers — the very essence of pastry. Yet there are important distinctions between them. Layer cakes, as I mentioned, are very simple things. Good ones are more cake than icing, and the cake itself is really the focus. The icing is more like a condiment. Plus, they’re usually made in just two layers.
French gâteaux can have several layers, one or more of which are made up of mousse, ganache or fruit filling, supported by thin layers of sponge cake. Thus for a gâteau — and I’m generalizing here — cake is not the centerpiece, it’s more of a structural element. Another important distinguishing factor is that gâteaux are usually made with a lot of fresh fruit, which obviously wilts rather easily. Thus a gâteau is typically intended to be eaten the same day it’s made.
Austrian tortes are likewise all about layers, and brother, can they ever have a lot of them. Six, eight, ten…you name it. Of course those layers are usually very thin, made of some sort of spongecake, frequently with finely ground nuts (like almonds, hazelnuts or macadamia nuts) added to the batter. The layers of a torte can be filled with either a cream or fruit filling, and the whole thing is frequently covered in a sheath of chocolate or fondant, which means that unlike gâteaux, they can last for days.
That’s about the best I can do on short notice. Europeans? Any of you can to chime in?