Prepare all ingredients:

Melt the chocolate in a bain-marie.

Off the heat, add the softened butter...

...then the 4 yolks one a a time.

Beat the very cold cream into chantilly (also use a cold bowl and cold whisk) by adding 20 g of icing sugar at the end.

Delicately mix it to the cooled chocolate.

Beat the 3 egg whites firm...

...by adding the rest of icing sugar at the end.

Delicately add them to the last preparation.

Place in the fridge for 15 minutes to firm up a bit.

Boil tea and whisky with the caster sugar for 2 minutes.

Count the number of biscuits necessary to coat the sides and bottom of the charlotte mold. Trim them to the right size. Dip the biscuit one side in the syrup of cooled tea.

Line the bottom and sides of the greased mold.

Add half of the mousse, cover with a layer of soaked biscuits.

Spread the rest of the mousse and cover with biscuits.

Cover with a plate and leave to firm up in the fridge for 6 hours.

Delicately remove your charlotte from the mold, decorate with mimosa and serve immediately.