Start with the base and melt 150g chocolate and 100g butter in a bain-marie.
Add the 4 egg yolks to this mix once cooled.
Add the flour and sugar, then slowly fold in 4 egg whites.
Pour into an upside-down tart mold and cook in the oven at 180c for around 25-30 minutes.
For the topping, melt 75g chocolate and 25g butter in a bain-marie (the rest of those ingredients).
Mix in 2 egg yolks and then fold in the 2 egg whites.
Pour this onto the base, then let cool in the fridge. Can be served with whipped cream.