Combine egg yolks, sugar and salt in a medium bowl and whisk until the color is a plate yellow.
4 Egg yolks, ¼ cup Granulated sugar, ⅛ teaspoon Kosher salt
Heat the heavy cream (for the custard) until bubbles just begin to form along the edges. Slowly pour hot cream into the egg yolk mixture, whisking, to temper.
1 ¼ cups Heavy cream
Return the custard to the saucepan. Gently heat, whisking often, until mixture thickens and coats the back of a spoon, about 6-8 minutes and reaches 175-180F. Don’t let it boil!
Remove from heat and stir in vanilla and chocolate. Let sit a few minutes to melt, then whisk until smooth. Transfer to a bowl and let cool completely.
1 teaspoon Vanilla extract, 7 oz Bittersweet chocolate
In the bowl of a stand mixer fitted with a whisk attachment, beat remaining 1 cup heavy cream until it reaches stiff peaks. Mix ⅓ of whipped cream into the chocolate mixture until smooth. Then use a spatula to gently fold the remaining whipped cream into the chocolate mixture in 2 parts, until no streaks remain.
1 cup Heavy cream
Transfer the mousse to a pastry bag or ziplock bag and pipe the mousse decoratively into your serving glasses of choice. Chill for at least 1-3 hours to set. Garnish with berries, candied rose petals, or chocolate-covered candies and enjoy chilled or allow the mousse to come to room temperature to serve for a softened texture and enjoy!
Optional garnish