Bake this chocolate mousse straight out of the freezer. It couldn't be easier.
14 ounces bittersweet chocolate, chopped
3/4 cup unsalted butter
6 large eggs, separated
1/4 teaspoon salt
1 cup sugar
How to Make It
Put chocolate and butter in a medium metal bowl and set bowl over (not touching) simmering water in a pot. Heat until chocolate is almost completely melted; remove from heat, stir until smooth, and set aside.
With a mixer fitted with the whisk attachment, whisk egg whites and salt in a bowl until foamy. With mixer still on, slowly rain in sugar and whisk until soft peaks form.
Stir yolks into chocolate mixture until completely blended. Using a rubber spatula, gently fold in whites. Divide mixture among 12 small freezer- and ovenproof coffee cups or ramekins (4 oz. each). Cover each cup with plastic wrap and freeze at least 3 hours and up to 2 weeks.
Preheat oven to 325°. Set ramekins on a rimmed baking sheet, remove plastic wrap, and bake until puffed, cracked on the edges, and just wet-looking in the center, 30 to 35 minutes. Let cakes cool 10 minutes before serving.