Chocolate Mousse Recipe

Melt chocolate and butter

Place the chopped bittersweet chocolate and butter in a heatproof bowl set over (but not touching) simmering water (double boiler). Stir occasionally until fully melted and smooth, about 4–6 minutes. Remove bowl from heat and let the chocolate cool slightly (4–6 minutes) but remain pourable.

Temper egg yolks

Whisk the 4 egg yolks with 1 tablespoon granulated sugar and 1 teaspoon vanilla in a medium bowl until pale and slightly thickened. Slowly stream about 1/3 of the warm melted chocolate into the yolk mixture while whisking constantly to temper the yolks. Then pour the tempered yolk-chocolate mixture back into the remaining melted chocolate, whisking until fully combined. Stir in a pinch of fine sea salt. Set aside to cool to lukewarm (about 5–8 minutes).

Whip cream

Chill a mixing bowl and the beaters for best results. Pour the cold heavy cream and 1 teaspoon confectioners' sugar into the chilled bowl. Whip on medium-high speed until soft peaks form — the cream should hold shape but still be silky, about 2–3 minutes. Do not overbeat. Reserve about one tablespoon for garnish if desired.

Fold cream into chocolate

Gently fold about one-third of the whipped cream into the cooled chocolate-yolk mixture to lighten it. Use a rubber spatula and fold with a cutting-and-turning motion. Once incorporated, fold in the remaining whipped cream in two additions until no streaks remain and the mixture is homogeneous and airy.

Beat egg whites

In a separate clean, dry bowl, add the 4 room-temperature egg whites and 1 teaspoon cream of tartar. Beat on medium speed until foamy. Gradually add the 2 tablespoons granulated sugar in a slow steady stream while increasing speed to high. Continue beating until glossy stiff peaks form (the peaks should stand up and not fold over), about 3–5 minutes.

Incorporate egg whites

Gently fold one-third of the meringue into the chocolate-cream mixture to lighten it, using a rubber spatula and careful strokes to preserve air. Once blended, fold in the remaining meringue in two additions until the mixture is uniform and airy. Stop folding as soon as there are no visible white streaks to avoid deflating the mousse.

Spoon or pipe the mousse into serving glasses or ramekins, filling them to desired level. Smooth the tops with an offset spatula if needed. Cover each with plastic wrap and refrigerate for at least 2 hours, preferably 3–4 hours, until set and chilled.

Just before serving, dust the tops with cocoa powder or sprinkle bittersweet chocolate shavings. Add the reserved tablespoon of whipped cream or a mint leaf for garnish if desired. Serve chilled.