GÉNOISE is the most popular all-purpose cake in France. Once you master the techniques for making this cake, the possibilities are endless. Basically a sponge cake made with butter, it is used to make round cakes, square cakes, and jelly rolls. Because of its firm texture, it can be cut into thin layers that—when layered with a variety of buttercreams, whipped creams, liqueur- or coffee-flavored syrups, sugar icings, toasted nuts, praline, and ganache—transform it into elaborate and delicious creations (see “Les Gâteaux”). For two good examples, try Chocolate Génoise with Grand Marnier Ganache and Gâteau Moka, which is a vanilla génoise with a coffee buttercream.
In the technique for making a classic génoise, there are two areas that can cause problems for cooks, inexperienced and experienced alike. The first is in the initial beating of eggs over heat—the warmth helps the eggs to increase their volume but can also be awkward and time consuming. And the second problem area arises when melted butter must be folded into this lightened egg mixture without deflating it.
To make the whole procedure easier, and to reduce the risk of failure, I do two things. Instead of beating the eggs over heat, I simply warm the eggs (in the shell) in a bowl of hot tap water while I assemble the other ingredients. Then I pour the water out of the bowl, dry the bowl, and crack the eggs into it while they are still warm. I then beat them with the sugar to produce a thick, firm batter in a relatively short time (5 to 8 minutes).
When it comes time to incorporate the butter, I use soft, partially melted butter in place of the traditional fully melted butter. And instead of adding it directly to the batter, I blend a small amount of batter into the butter first to make its consistency similar to the batter, and thereby easier to fold back in.
If you are familiar with French cake recipes, you will notice that I have reduced the amount of sugar in the classic sugar syrup by at least 75 percent, since I find most classical French cakes too sweet.