Preparation Steps

• Melt the dark chocolate in a heatproof bowl over a saucepan of simmering water (bain-marie) or in the microwave. Let it cool slightly.
• In a large bowl, whisk the heavy cream, powdered sugar, and vanilla extract until medium peaks form. Gently fold in the dissolved espresso.
• In a separate bowl, whisk the egg yolks until light in color. Fold the slightly cooled melted chocolate into the egg yolks until well combined.
• To make the Italian meringue, combine granulated sugar and water in a small saucepan. Heat over medium heat until the syrup reaches 240°F (115°C) on a candy thermometer.
• Meanwhile, in a clean, grease-free bowl, whisk the egg whites until soft peaks form. Slowly pour the hot sugar syrup into the egg whites in a thin stream, continuing to whisk until the meringue is glossy and stiff peaks form and the bowl cools.
• Gently fold the chocolate-egg yolk mixture into the whipped cream. Then, carefully fold in the Italian meringue in two additions until just combined, being careful not to deflate the mousse.
• Divide the mousse among serving glasses or a large bowl. Cover and refrigerate for at least 4 hours, or preferably overnight, before serving.