1. Prepare the Crust:

1. Preheat oven to 350°F (175°C). Mix cookie crumbs and melted butter, then press into the bottom of a 9-inch springform pan.
2. Bake the crust for 10 minutes, then let cool completely.
3. Melt chocolate in a heatproof bowl over simmering water. Let cool slightly.
4. Whip heavy cream until stiff peaks form. Set aside.
5. Beat egg yolks with sugar until pale. Stir in vanilla and melted chocolate.
6. In a separate bowl, beat egg whites with salt until stiff peaks form.
7. Gently fold whipped cream into chocolate mixture, then fold in egg whites.
8. Pour mousse over the cooled crust and refrigerate for at least 4 hours or overnight.
9. Garnish with chocolate shavings before serving.