Chop or shave the chocolate and keep it in the refrigerator.

Prepare three bowls: a large one for the whipped cream, a medium one for the egg whites, and a small one for the egg yolks.

In the small bowl, mix the egg yolk and liqueur well with a whisk. Add the extract if you have it.

In the medium bowl, beat the egg whites with a hand mixer on high speed. Once they start to thicken, add 1 tablespoon of sugar in two parts to make a firm meringue.

Without washing the mixer blades, add the remaining sugar to the large bowl and whip until soft peaks form.

Add about half of the meringue from step 5 to the mixture from step 4 and mix well with a whisk.

Add the remaining meringue, the mixture from step 6, and the chocolate to the large bowl. Mix with a spatula until combined. Freeze until firm (no need to stir during freezing).