Melt the Chocolate:

Place the chopped chocolate in a heatproof bowl.

Using a double boiler or microwave, melt the chocolate until smooth. Allow it to cool slightly.

Prepare the Egg Yolks:

In a separate bowl, whisk together the egg yolks, half of the sugar, and vanilla extract until well combined.

Combine with Melted Chocolate:

Gradually whisk the melted chocolate into the egg yolk mixture until smooth and well incorporated.

Whip the Egg Whites:

In a clean, dry bowl, beat the egg whites with a pinch of salt until soft peaks form.

Gradually add the remaining sugar and continue to beat until glossy and stiff peaks form.

Incorporate Egg Whites:

Gently fold the whipped egg whites into the chocolate mixture using a spatula. Be careful not to deflate the egg whites; the goal is to create a light and airy texture.

Whip the Cream:

In another bowl, whip the heavy cream until it holds stiff peaks.

Final Assembly:

Fold the whipped cream into the chocolate mixture until smooth and evenly combined.

Chill:

Spoon the mousse into individual serving glasses or a large bowl.

Refrigerate for at least 4 hours, allowing the mousse to set and develop its rich flavor.

Garnish and Serve:

Before serving, garnish with whipped cream and chocolate shavings if desired.