Soak the gelatine sheets in cold water for about 5 minutes.

Heat the heavy cream and milk in a saucepan over low heat until it just starts to simmer.

In a mixing bowl, whisk the egg yolks until they lighten in colour.

Slowly pour the hot cream mixture into the egg yolks while whisking continuously to prevent the eggs from cooking.

Return the mixture to a pot and cook it, whisking constantly on medium heat, to 185ºF/85ºC, without boiling.

Squeeze the excess water from the gelatine sheets and add them to the cream mixture, stirring until the gelatine is completely dissolved.

Add the melted dark chocolate to the cream mixture and whisk until smooth, then allow it to cool to room temperature.

Whip the heavy cream in a separate mixing bowl until stiff peaks form.

Gently fold the whipped cream into the chocolate mixture until fully incorporated.

Pour the mousse mixture into serving cups or a large desired dish.

Chill the mousse in the refrigerator for at least 2 hours or until set.

Serve chilled and enjoy with chocolate sauce or other creative toppings.