Directions

1. In a mixing bowl, beat the egg yolks and sugar with an electric mixer set on medium speed until pale, creamy, and starting to thicken, about 5 minutes.
2. With clean beaters, whip the cream in a non-plastic bowl on medium speed until fluffy and the cream forms stiff peaks. Use a rubber spatula or wire whisk to fold 1/3 of the yolk mixture into the whipped cream. Gently run the spatula through the center of the bowl, then around the sides of the bowl, repeating until fully incorporated. Add the remaining yolk mixture and then the Irish cream liqueur, folding just until incorporated.
3. In a microwave-safe bowl, heat the chocolate very gently on low power just until melted; stir to dissolve any lumps. Very gently fold the chocolate into the Irish cream mixture as before, keeping as much fluffy volume as possible. With clean beaters, beat the egg whites on medium-high speed in a non-plastic bowl to stiff peaks; gently fold the egg whites into the chocolate mixture until evenly incorporated. Spoon the mousse into individual dessert cups or glasses, and chill for 4 to 6 hours.