This delicious mousse was inspired by the silky and spiced flavors of Robusta coffee beans, and brings that texture + those flavors to life in this chocolate-y, light, and airy French dessert.
Beat the heavy cream in the bowl of an electric stand mixer fitted with the whisk attachment until still peaks form. Transfer to another bowl, cover, and refrigerate.
In the top of a double boiler over low heat, combine the egg yolks, coffee, brown sugar, cinnamon, nutmeg, and 1/4 teaspoon kosher salt. Cook the mixture, whisking constantly, until foamy and it's roughly doubled in volume. About 3 to 5 minutes depending on the intensity of your heat source.
Remove the top bowl from the double boiler, add the chocolate chips, and whisk constantly until they're melted and the mixture is smooth. Set aside to cool to room temperature, whisking every couple minutes to help steadily lower the temperature of the mixture.
In the bowl of an electric mixer fitted with the whisk attachment, beat the egg whites until they're slightly foamy, then add the granulated sugar and continue to beat them until stiff glossy peaks form. (NOTE: If you are using the same stand mixer and whisk that you did to make the whipped cream, it is **very** important to wash them very thoroughly in between. If there is every a smudge of fat still in the bowl or whisk, the egg whites won't stiffen properly).
Fold the egg whites into the chocolate mixture in three additions. Fold the whipped cream into the chocolate mixture in two additions. Divide the mixture between 6 4-ounce jars or ramekins, sprinkle the tops with the flake kosher sea salt and a pinch of cinnamon for garnish. Cover and refrigerate until serving.
Adapted from Bon Appetit