The best chocolate mousse

Ingredients:

• 1 and 3/4 cups chilled heavy cream
• 1 large egg
• 2 large egg yolks
• 1/4 cup sugar
• 1 tsp instant espresso powder
• 1 tsp vanilla extract
• 0.5 tsp salt
• 110 g of quality dark chocolate, chopped
• 110 g of quality dark chocolate, chopped
• Special equipment: four ramekins with a volume of 120 ml.

Preparation:

1. In a medium bowl, beat 1 cup heavy cream until soft peaks form. Set aside.
2. In a medium heatproof bowl, combine the egg, egg yolks, sugar, espresso powder, vanilla extract, salt, and 1 tablespoon water and whisk until smooth. Place the bowl over a medium saucepan of simmering water (the bottom of the bowl should not touch the water). Whisk constantly until the mixture is pale, hot to the touch, and has almost doubled in volume, about 4-6 minutes, scraping down the sides of the bowl occasionally with a spatula if necessary. Remove from the heat and continue whisking until cool, about 2 minutes.
3. Place the chopped chocolate in a heatproof bowl over a pan of simmering water (the bottom of the bowl should not touch the water). Stir occasionally with a spatula until the chocolate is melted and smooth. Remove from heat and stir gently for about 3 minutes to cool slightly.
4. Whisk the egg mixture with the melted chocolate in 3 additions until smooth. The mixture may be very thick. Using a silicone spatula, gently fold the whipped cream into the chocolate mixture in 3 additions until completely incorporated. It's important that the chocolate mixture isn't hot so it folds smoothly into the whipped cream.
5. Divide the chocolate mousse among four 120ml ramekins and refrigerate for about 1 hour to set.
6. Whipped cream:
   
   Whip the remaining 3/4 cup chilled heavy cream until stiff peaks form. Top each mousse with whipped cream and serve. If you prefer a softer mousse, let the molds sit at room temperature while you whip the cream.
   
   Note
   
   You can whip the cream with either a whisk or a mixer.