Dark Chocolate Mousse

6 servings · 25 minutes preparation · 5 minutes cooking · 240 minutes cooling, chilling or resting

Ingredients

• 200 g (7 oz) bittersweet chocolate (64% to 70% cocoa solids), finely chopped
• 45 ml (3 tbsp) unsalted butter, cubed at room temperature
• 4 large eggs, separated cleanly into yolks and whites
• 45 ml (3 tbsp) granulated sugar, divided
• 1 ml (1/4 tsp) fine sea salt
• 2 ml (1/2 tsp) pure vanilla extract
• 15 ml (1 tbsp) freshly brewed hot espresso or warm water
• 120 ml (1/2 cup) cold heavy whipping cream (minimum 36% milkfat)
• 15 g (1 tbsp) shaved dark chocolate, for serving

Step-by-step instructions

1. Set a heatproof glass bowl over a saucepan with 2 cm of gently simmering water over low heat, ensuring the bowl bottom does not touch the water. Add the chopped chocolate, cubed butter, and warm espresso, stirring occasionally with a silicone spatula until smoothly melted, glossy, and registering roughly 45 C (113 F).
2. Remove the chocolate bowl from the steam and let it sit on the counter for 5 to 7 minutes until barely warm to the touch, roughly 38 C (100 F). Whisk the 4 egg yolks vigorously in a separate small bowl with half of the granulated sugar, then gently incorporate them into the melted chocolate base.
3. In a chilled metal bowl, whip the heavy cream and vanilla extract using a hand mixer on medium speed until soft, billowy peaks form, roughly 2 to 3 minutes. Take care not to overwhip the cream into stiff clumps; immediately transfer it to the refrigerator while preparing the egg whites.
4. In a spotlessly clean, grease-free mixing bowl, whip the egg whites with the sea salt on medium-low speed until foamy. Gradually rain in the remaining sugar while increasing mixer speed to medium-high, continuing to whip until firm, glossy peaks form that hold their shape when the beaters are lifted, approximately 3 minutes.
5. Lighten the chocolate-yolk mixture by vigorously stirring in one-third of the whipped egg whites with a flexible spatula until completely homogeneous. Gently fold in the remaining whites in two additions using slow, sweeping under-and-over motions, cutting through the center to preserve the delicate aerated structure without leaving visible white streaks.
6. Fold the chilled whipped cream into the aerated chocolate base using the same gentle sweeping motion until evenly distributed and uniform in color. Divide the mousse evenly among 6 small glasses or ramekins, smoothing the tops lightly with a spoon, and wipe any drips clean from the glass rims.
7. Cover each individual serving dish tightly with plastic wrap without touching the surface of the mousse. Transfer the ramekins to the refrigerator and chill for at least 4 hours, or preferably overnight, until thoroughly set, chilled throughout, and firm yet tender to a spoon, before finishing with shaved dark chocolate.

Kitchen notes

Cleanliness is essential when aerating egg whites; ensure your whisk and bowl are thoroughly washed with hot soapy water and dried completely, as even a tiny speck of yolk or oil can hinder volume expansion. Pay close attention to chocolate temperature when folding: if the melted chocolate is too cold, it will seize into hard flecks upon contact with cool ingredients; if too hot, it will deflate your whipped components.

Storage & make-ahead

Store individual portions tightly covered with plastic wrap in the refrigerator for up to 3 days. Do not freeze, as the ice crystal formation disrupts the fat emulsion and causes water separation upon thawing. Serve directly from the refrigerator to maintain stability.