Place the semisweet chocolate in a large microwave-safe bowl.

Microwave on high for 1 minute.

Stir the chocolate.

Microwave for another 30 seconds until completely melted.

Set aside to cool slightly.

In a clean bowl, beat the egg whites with an electric mixer at high speed until medium peaks form.

Set aside the beaten egg whites.

In a chilled clean bowl, beat the heavy cream with an electric mixer at high speed until medium peaks form.

Mix the egg yolks and tequila into the melted chocolate until smooth.

Gently fold in 1/3 of the beaten egg whites into the chocolate mixture to lighten it.

Gently fold in the remaining 2/3 of the beaten egg whites, being careful not to deflate the mixture.

Gently fold in the whipped cream, taking care not to overmix.

Spoon the mousse into 4 martini glasses.

Using a vegetable peeler, shave chocolate on top of the mousse.

Garnish with fresh mint leaves.

Chill in the refrigerator for at least 1 hour, or up to 1 day ahead of serving.