This One-Ingredient Chocolate Mousse Recipe Is Pure Magic

With Genius Recipes correspondent Kristen off for a few months trying to raise a genius newborn, we're revisiting the column's Greatest Hits with brand-new videos—and hearing from a few special surprise guests. Wish her luck! (And keep sending those tips.)

This week, a completely forgiving, undemanding, and lovable chocolate mousse.

It took a brilliant, adventurous chemist to discover the simplest way to make chocolate mousse at home.

"I invented it—but it was so easy, I'm embarrassed!" Hervé This told Wired magazine in 2007.

He also invented the study of (and the very phrase) molecular gastronomy. But his book of the same name doesn't read like a science manual and, as far as I know, nothing gets spherified.

The book instead is about simple, scientific surprises and improvements in home cooking. He explains everything from getting crisp skin on a roast chicken (don't baste with the juices) to whether gnocchi are truly done when they bob to the surface (not necessarily).

... And how to make a flawless, creamy chocolate mousse out of just chocolate and water. Oh yes he did.

It's just like whipping cream: Heavy cream (itself an emulsion of milk fats and water) froths up readily when whisked in a chilled bowl, right? So all you have to do is aim for a ratio of water to fat (cocoa butter here) that mimics that of whipping cream. (And what of emulsifiers, you ask? The lethicin in chocolate does the trick.)

Melt the chocolate and water together, cool it over an ice bath, and whisk till you have mousse. Still baffled? Watch Heston Blumenthal pull it off in the video below, which was sent to me by two different, equally excited Food52ers, Cade and drbabs.

Like other emulsions (vinaigrette, aioli), it works as if by magic. As you whisk, microscopic bits of water get suspended in the fat, thickening it and making it seem creamier. Then still more air is whipped into it and the cooling chocolate crystallizes around the air bubbles to make a remarkably stable foam, aka mousse.

The best thing about it—aside from its dumb-founding magicalness—is that it tastes like pure, unobstructed chocolate. There's no cream or egg to confuse the issue, like in normal mousses. (It also happens to be vegan, if you use dark chocolate without any added milk.)

You can get all kinds of different textures, by stopping at different points as you whisk:

1) For a mod, flat-topped look, like sexy pot de creme: Pour it into ramekins while it's thickened, but still a bit warm.

2) When it gets to the texture of thick pudding, you can spoon it into a glass parfait-style, like little chocolate snowdrifts (as in our photos). At this stage, you could even use it to frost a cake.

3) Whip it just a bit further for something fluffy you can ball up in an ice cream scoop, if that's what you're going for. Beyond this, and it gets crumbly and dry (though still tasty).

This all happens fast as the mixture cools, so chances are you'll go too far on your first try. But if this happens, Mr. This is unfazed—just return it to the pan, melt it, and start over. (It's even easier than saving overwhipped cream, which he's also figured out.)

Once you have the rhythm down, you can flavor it as you wish with liqueurs or coffee or spices, sweeten it to your liking, or just keep it dark and intense. In all of these scenarios, a little whipped cream up top is never a bad idea.

Hervé This' Chocolate Mousse

Adapted from Molecular Gastronomy: Exploring the Science of Flavor (Columbia University Press, 2008)

Serves 4

8 ounces chocolate (we used 70% bittersweet—choose a high quality chocolate you love)
3/4 cup (6 ounces) water
ice cubes
freshly whipped cream for topping (optional)

See the full recipe (and save and print it here).

Got a genius recipe to share—from a classic cookbook, an online source, or anywhere, really? Perhaps something for beginners? Please send it Kristen's way (and tell her what's so smart about it) at [email protected].

Photos by James Ransom