I was really craving something light. But chocolatey. Not a double-venti mochafrappadingdong either. Something simple, but tasty and nice. But what? Then it hit me like a ton of whipped cream: chocolate mousse!
Chocolate mousse was my favorite (scratch that; only) fancy restaurant dessert as a kid. It's traditionally a mixture of whipped egg whites, egg yolks, dairy, and flavoring. The flavoring can be anything from spices to fruit puree, but when most people hear "mousse" they think "chocolate." And I have no problem with that.
So what makes a great chocolate mousse? Well, it really depends on your tastes. Some people like a sweet, creamy chocolate mousse that's lighter than air. Others prefer a darker, denser flavor and texture. You can make mousse with milk, white, or dark chocolate, and it's easy to punch up the flavor with espresso, liqueur, sea salt, or any number of spices.
There are all kinds of variations on basic recipe methods—from the simplest preparation of egg whites, yolks, and chocolate, to those involving cream and butter. Some use gelatin instead of eggs, and some even call for a custard that's folded into the whipped base.
All of these recipes will turn out differently, of course; but the basic steps are similar. Melt the chocolate and/or butter, whip the egg whites and/or cream, fold them together, allow to set. Simple, delicious, and elegant.
That being said, there are a couple main things you want to keep in mind when making mousse. First, you want to make sure the melted chocolate is at the right temperature when you fold it into the aerated whites/cream. Too warm and it will cook or deflate the base; too cool and it will seize and separate into chunks. It should feel just warm when you dab it on your lip (the best way to test chocolate temperature, as fingers tend to be cooler than body temp).
You also want to fold, not stir, the chocolate mixture into the aerated base. The idea is to mix without deflating. In pastry school, they encouraged us to think of making a "J" shape with the spatula while folding, which always helped me.
This recipe is from one of Pierre Hermé's books, and is therefore bulletproof. You'll see how specific the directions are, which is incredibly helpful. Feel free to use a hand mixer, or even your own muscle power, to beat the egg whites.
What's interesting about this recipe is that it uses whole milk instead of cream, making the end result even lighter. Correspondingly, I'd recommend using chocolate that's no more than 60 to 65% cacao, as the flavor could easily overwhelm the delicate texture of the mousse. As for adornment, this really needs none. A dollop of whipped cream or a couple of fresh raspberries certainly wouldn't kill anyone, though I consider it gilding the lily; but go with your gut.
It's going to taste amazing no matter what.