I once read an interview with the French chef Alain Ducasse, in which he said: “Sugar is the enemy of chocolate.” Mr. Ducasse owns his own chocolate company, which makes extraordinary bars and truffles, so I’d be inclined to take his word for it, even if all of my experience as a baker didn’t back up his statement. Undoubtedly, excessive sugar dulls and masks chocolate’s singular flavor.
Yet at the same time, sugar, in just the right quantity, brings chocolate to life, tempering its bitterness and bringing subtler flavors to the forefront. So when I set out to develop my ideal chocolate layer cake, my goal was to add just enough sugar to produce both a cake and a frosting that were flavorful but not noticeably sweet. The final cake had to be moist, but not heavy, and pack considerable chocolate flavor without being overpowering.
For that, I skipped melted chocolate in favor of cocoa powder. Melted chocolate tends to dry out cake batter, and unless you’re using 100 percent unsweetened chocolate, adding bar chocolate also means adding sugar, giving you a little less control over the final sweetness. Use the best-quality cocoa you can find, and make sure it’s labeled “Dutch process.” This means the cocoa that has been alkalized, neutralizing some of the natural acidity and giving the cocoa a darker color and a rounder, more roasted flavor.
To ensure a supple cake, I opted for an oil-based batter instead of a butter-based one. Oil is liquid at room temperature, so oil-based cakes tend to resist drying out better than butter-based ones. But because a little bit of butterfat flavor is always welcome, I use crème fraîche (or sour cream) in place of a more traditional liquid, such as milk or buttermilk. The acid in crème fraîche also reacts with the baking soda in the dry ingredients, creating lift so the cake bakes up light and bouncy.
Layer cakes can be a little intimidating for some people, but provided you have a mixer, assembling the batter couldn’t be easier. It’s made using a method that’s similar to the “reverse creaming” method popularized by the cake expert Rose Levy Beranbaum, in which the dry ingredients, sugar, fat and a portion of the liquid are first mixed together before the eggs and remaining liquid are added. Not only does this technique allow you to measure nearly everything directly in the mixing bowl, but it also results in a very tender cake that bakes into relatively flat layers, making assembly a little easier.
The frosting is where melted chocolate shines (literally), giving it a high gloss and ultra-silky texture. Rather than employing egg white-based Swiss or Italian meringue buttercreams, which are fluffy and a little technical, I make a variation on German buttercream, which calls for whipping butter into a pastry cream base for a denser texture. After cooking a quick pudding on the stove, I stir in a high proportion of chopped chocolate until melted, then beat in the butter to make a frosting that manages to be smooth, dense and light all at the same time.
As with any cake made with a butter-based frosting, this one must be served at room temperature to safeguard the frosting’s texture (when cold, buttercream hardens). You can absolutely make it ahead and refrigerate it — the flavor of oil-based cake tends to improve over time — just remember to give it several hours to reach room temperature before serving. While I would definitely describe this cake as “not too sweet,” unlike denser chocolate cakes that saturate your palate, it’s balanced and not overly intense, so the last bite is as good as the first.
