Melt 200 gr of chocolate with a spoonful of milk and leave to cool. Mix the butter at room temperature with the egg yolks and the sugar until the mixture is fluffy and smooth. Add to the mix the two tablespoons of four.
Add the melted chocolate to the butter mix. Whisk the egg whites until stiff then carefully incorporate them in the butter and chocolate mix. Place the cake mix into buttered and floured cake mould and bake at 200° for 30 min.
Leave the cake to cool. Then melt the remaining 100 gr of chocolate with a spoonful of milk and spread the melted butter over the cake.