250g Chocolate (Menier Patissier), 52% cocoa (i.e. not too strong)
50g butter
2 heaped tea spoon full of icing sugar
1 shot of cointreau (circa 3-4 tbl spoons)
4 eggs

Get a bowl of the right size for the mousse – large enough to accommodate the chocolate and the egg whites

Melt chocolate with the butter in a bain marie/microwave; mix it together so that it’s nice and smooth, don’t beat it, but do keep it as compact as possible at the bottom of the bowl. Add in the icing sugar, cointreau, and yolks of egg, keeping it compact all the time. Whip up the egg whites until stiff; fold everything together (still keeping it as compact as possible) in the the bowl and place in the freezer for at least 24 hours (or for as long as you want to keep it). When you want to eat it, give it a few hours to defrost before serving.