Ingredients

• 8 ounces Dark Chocolate(70% cacao or higher, high-quality)
• 2 tablespoons Unsalted Butter
• 4 Large Eggs(separated)
• 1 cup Granulated Sugar(divided)
• 0.25 teaspoon Pinch of Salt
• 1 teaspoon Vanilla Extract
• 0.5 cup Heavy Cream(cold)
• 1 teaspoon Cocoa Powder(for dusting (optional))

Instructions

1. 1

   Chop the dark chocolate into small pieces and combine with the unsalted butter in a heatproof bowl. Set the bowl over a saucepan of simmering water (double boiler), ensuring the bowl doesn't touch the water. Stir occasionally until the chocolate and butter are completely melted and smooth. Remove from heat and let cool slightly.

2. 2

   In a separate medium bowl, whisk the egg yolks with 1/4 cup of the granulated sugar, the pinch of salt, and vanilla extract until the mixture is pale yellow and thick, about 2-3 minutes. Gradually fold the slightly cooled melted chocolate mixture into the egg yolk mixture until well combined.

3. 3

   In a clean, dry bowl, whip the heavy cream until soft peaks form. Set aside.

4. 4

   In another very clean, dry bowl, using an electric mixer with clean beaters, beat the egg whites on medium speed until foamy. Gradually add the remaining 3/4 cup granulated sugar, increasing the speed to high, and continue beating until stiff, glossy peaks form. Be careful not to overbeat.

5. 5

   Gently fold about one-third of the whipped cream into the chocolate mixture to lighten it. Then, gently fold in the remaining whipped cream until just combined.

6. 6

   Carefully fold about one-third of the whipped egg whites into the chocolate mixture to lighten it further. Then, very gently fold in the remaining egg whites in two additions, taking care not to deflate the mixture. Use a large rubber spatula and a gentle 'cut and fold' motion, scraping the bottom of the bowl and folding it over the top.

7. 7

   Divide the mousse evenly among 4 individual serving glasses or ramekins. Smooth the tops lightly.

8. 8

   Cover the ramekins loosely with plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow the mousse to set and flavors to meld.

9. 9

   Before serving, you may dust the mousse with a little cocoa powder or garnish with chocolate shavings, if desired.