- 2½ cups heavy cream
- 4 ounces 99% unsweetened chocolate, coarsely chopped
- 6 large egg yolks
- 1¼ cups granulated sugar
- 1 cup whole milk
- ½ cup finely ground cacao nibs or 62% semisweet or 70% bittersweet chocolate
- To serve the mousse in 5- to 6-ounce ramekins, cut 6 strips of parchment or waxed paper about 4 inches wide and 1 inch longer than the circumference of the ramekins. Fold the strips lengthwise in half Cut 6 long pieces of twine. Wrap each ramekin in a strip of paper, allowing the paper to extend about 1 inch over the top of the ramekin, and tie the collar securely with a piece of twine.
- Place ¾ cup of the cream in a small saucepan and bring to a simmer. Turn off the heat, add the chocolate, and let stand for 2 minutes. Stir until the chocolate is melted.
- In a medium bowl, whisk the egg yolks and sugar until thickened.
- In a saucepan, bring the milk to a simmer over medium-low heat. As soon as it begins to simmer, add a few tablespoons of the warm milk to the yolk-sugar mixture, whisking constantly. Pour about half the warm milk into the bowl, while whisking, then return the mixture to the saucepan and stir constantly for about 8 to 10 minutes, or until the custard thickens and reaches 175°F.
- Meanwhile, fill a large bowl with ice water. Strain the custard through a fine-mesh strainer into a large bowl set over the ice water. Stir until it is cool to the touch, then remove from the ice water.
- In a large bowl, whip the remaining 1¾ cups cream until it forms very soft peaks. Stir the chocolate mixture if it has separated, and fold into the cooled egg mixture. Fold in the whipped cream.
- Spoon the mousse into the prepared ramekins or into a serving bowl. If using the ramekins the mousse should extend about ½ inch over the rim of each ramekin. Place the ramekins on a tray and lay a piece of aluminum foil over the top. Freeze for at least 6 hours or up to 2 days.
- About 5 to 10 minutes before serving, remove the mousse from the freezer. Remove the collars, and press the nibs or ground chocolate around the sides of the mousse.