For the warm chocolate tart, separate eggs and beat egg whites until stiff.
Break chocolate into pieces, pour into unperforated rice bowl and cover. Let melt for about 10 minutes. Stir in melted butter.
Mix yolks, sugar and flour and add to chocolate. Fold in beaten egg white.
Butter the ramekins, sprinkle with sugar and pour in the mixture.
Then let the ramekins cook in the largest bowl for 30 minutes. Then turn out the warm chocolate tartlet and sprinkle with powdered sugar.