For a good number of her formative years, my friend Jennifer was constitutionally incapable of following a recipe. It wasn’t an issue of willful aversion, nor or of culinary rebellion, but every time she tried to follow directions, something went horribly wrong. As a pre-teen, for example, Jen whipped up a batch of her mother’s famous banana nut bread as a gift for her teachers, but sadly, her loaves were destined for a different type of fame—an infamy reserved for flat, gummy quick breads entirely lacking in flour. Even cake mix was iffy: one babysitterless night, we together watched a straight-from-the-box angel food cake nearly explode in her parents’ oven. Today, after a recovery period of a decade or two, Jen has patched up her relationship with recipes, but she’s still not one to follow the rules. Instead, she’s built an impressive record on taking a recipe and running with it. She makes a beautiful improvised beet vinaigrette, an unusual fiddlehead fern ratatouille, and a fiery off-the-cuff chile-balsamic sauce. And, as I learned one foggy night last week in her airy San Francisco apartment, she has a rare genius for finding rogue recipes—the type that suit her best, after all—and saving them from the rubbish bin. Take, for example, her devastatingly good chocolate mousse.

A month or two ago, Jen and her husband Dave, both oenophiles with a weakness for California’s small Mom-and-Pop vintners, noticed that their wine rack was looking a bit overstuffed. So they asked a handful of friends to help them “get rid” of a few bottles, and within 24 hours, they had a dozen people and a party in their living room. There were breads, local cheeses, and fruits, but to go with the reds, Jen wanted to serve something chocolate, preferably simple, creamy, and very, very dark. So she typed the words “chocolate ice cream” into Epicurious, and she promptly fell in love—with a very questionable recipe. Its ratings were solidly mediocre, its reviewers ambivalent at best. “This should not be called ice cream,” one fumed; “It doesn’t come close to resembling the texture of ice cream. It’s like a rich, smooth, cold fudge. I even tried cutting down the eggs and it still wasn’t the right texture.” “It’s like eating frozen chocolate mousse, not really ice cream,” another noted somewhat disapprovingly. This was clearly a very misunderstood, very badly misnamed recipe. What others might call a washout was exactly what she wanted. As I said, she has a certain genius.

Needless to say, the stuff is almost exactly as its reviewers described it, and happily so: a rich, smooth, frozen chocolate mousse, somewhere between gelato, frozen custard, and whipped cream, dark and complex and fearfully good.

More dense than the average mousse but with the whipped texture of a not-quiet-frozen ice cream, it is hard to pinpoint* but alarmingly easy to eat. The guests at Jen and Dave’s party had no trouble tucking it away, and last week, neither did we, even after a generous farmers’ market dinner of heirloom tomatoes with balsamic vinegar and Stonehouse olive oil; fresh gnocchi topped with morels and brown button mushrooms sautéed in olive oil, white wine, and lemon zest; and Acme pain au levain with Cowgirl Creamery cheeses. As Jen scooped the mousse, Dave poured purply glasses of delicate Homewood zinfandel port, and we sat around the candlelit table, chilly gusts of night air blowing in through the open window. Our dessert spoons sighed through the mousse, and so did we. Sometimes “bad” recipes are awfully good.

*Jen has yet to decide on an appropriate name for this recipe. She tends to refer to it as “my chocolate dessert,” “that chocolate dessert,” or “something with tons of chocolate and cream.” None of these titles, however, do it justice, and neither does an analogy we invented after a few glasses of wine: It’s like Cool Whip! It doesn’t freeze solid! It’s like chocolate Cool Whip! The name I have chosen below is my attempt to strike a happy—and fitting—medium.

Dark Chocolate Mousse Ice Cream
Adapted from Epicurious

If time permits, try to make this mousse a day or so ahead of time, so that it has time to properly set up. When it comes to serving, Jen has presented it in several different ways: in bowls; in little high-ball glasses with a few fresh raspberries on top; and, for a picnic, in tiny paper Dixie cups with a dollop of whipped cream. However you choose to serve it, start with small portions; this is serious stuff. And if you want to gild the lily, a ruby or vintage port, or perhaps a black Muscat dessert wine, makes for a lovely accompaniment.

1 cup whole milk
1 cup heavy cream
½ teaspoon vanilla
7 ounces best-quality 70% dark chocolate, finely chopped (for her most recent go, Jen used closer to 9 ounces, with superlative results)
½ cup plus 3 tablespoons sugar
3 tablespoons water
6 large egg yolks
1/8 teaspoon salt

Bring the milk, cream, and vanilla just to a boil in a small saucepan; then remove from heat and keep warm, covered.

Place the chopped chocolate in a large heatproof bowl.

Stir together ½ cup sugar with water in a medium heavy saucepan, and bring it to a boil over moderate heat, stirring until the sugar is dissolved and washing down any sugar crystals on the side of the pan with a pastry brush dipped in cold water. Boil the syrup, without stirring, gently swirling the pan and washing down crystals, until mixture is a deep golden caramel, about 10 minutes. Remove the pan from the heat, and carefully whisk in the warm cream mixture (the mixture will steam vigorously, and caramel may harden). Cook over low heat, whisking, until the caramel is dissolved.

Beat the yolks with the salt and the remaining 3 tablespoons sugar in a large bowl, using an electric mixer at high speed, until tripled in volume and thick enough to form a ribbon that takes 2 seconds to dissolve into mixture when the beater is lifted, 3 to 4 minutes in a stand mixer or 6 to 8 with a handheld one.

Add the hot caramel mixture to the yolks in a slow stream, whisking, then transfer the custard to the medium saucepan. Cook over moderately low heat, stirring constantly, until the custard is slightly thickened and registers 170°F on a candy or instant-read thermometer. Do not allow it to boil.

Press the custard through a fine-mesh sieve into the bowl with the chopped chocolate, and let stand 1 minute. Whisk the mixture until smooth.

Cool to room temperature, stirring occasionally, about half an hour.

Freeze the custard in an ice cream maker; then transfer it to an airtight container and put it in the freezer to harden, at least 1 hour and up to 24 hours. The mousse will keep well in the freezer for up to a week. Allow it to rest at room temperature for 10 minutes or so before serving.

Yield: about 1 quart.