1. Mix butter and sugar well in a bowl until it become like a cream.
2. Melt 250 gr plain chocolate in a bain-marie.
3. Blend the chocolate into the mixture.
4. Separate the white and the yolk of eggs.
5. Add the yolks into the mixture.
6. Give the flour a sieve, mix with yeast powder and blend it into the composite.
7. Whisk the egg whites until stiff and stir it slowly into the mixture.
8. Mix the ingredients well.
9. Ladle the composite into a cake tin greased (about 25-28 cm in diameter).
10. Put it in an oven (180 °C - 50 min).
11. Let it cool down and bisect it carefully in two discs.
12. Spread the apricot jam onto a disc.
13. Reassemble delicately the discs of the cake.
14. Melt the rest of the plain chocolate (250 gr) in a bain-marie.
15. Spread the cake with the liquid chocolate well.
16. Let it cool down and... eat it! :-)