Step 1

Heat a pot over medium or medium high heat, with about 2 - 3 inches of water. Bring it to a simmer. This will be used as a double boiler / bain marie, for the yolks and egg whites.

Step 2

Place the chocolate, butter, and salt in a microwave safe bowl, and microwave it in 20 - 30 second intervals, stirring in between. When the chocolate chips are about 75 - 80% melted, stir the chocolate butter mixture until all of the chocolate is melted. Set aside until needed.

Step 3

In a large metal bowl, place the egg yolks, water, vanilla, and half of the sugar. Whisk to combine. Place the bowl over the pot of simmering water. Heat the egg yolks to 170°F while constantly whisking. Once heated, remove from the heat.

Step 4

Add the butter and chocolate mix, and the bourbon (if using) into the egg yolk mix. Mix until well combined and then set aside.

Step 5

In a clean, dry, metal mixing bowl, place the egg whites and the rest of the sugar. Heat the egg whites over the pot of simmering water while constantly whisking, until the mixture is heated to 170°F.

Step 6

When the egg whites are heated, remove the bowl from the double boiler and attach it to your stand mixer with a whisk attachment. You can also use a hand mixer.

Step 7

Whisk the egg whites until they are glossy and you have mid peaks. Mid peaks is beyond soft peaks, but not quite at stiff peaks.

Step 8

Add about ¼ of the egg whites to the chocolate yolk mix, and mix it in to "loosen" the chocolate base.

Step 9

Add the rest of the egg whites and carefully fold it in, until it's about 70 - 80% mixed through (some egg white streaks are still visible). Set aside.

Step 10

Add the heavy cream into the same bowl that you used to whisk the egg whites. Whisk until you have soft peaks.

Step 11

Add this cream to the chocolate mousse base and fold it in until mixed through.

Step 12

Place the chocolate mousse in a shallow dish, or divide between 6 individual serving dishes.

Step 13

Cover with plastic wrap and let it chill overnight.

Step 14

Remove the chocolate mousse from the fridge about 30 - 45 minutes before serving. For best flavor, the mousse should not be completely chilled (which dampens the chocolate flavor), only a little cold.

Step 15

Top it with shaved chocolate or whipped cream, and serve.