Step 1: Preheat the oven to 180°C.
Step 2: Butter pastry circles and place them on a baking sheet lined with baking paper.
Step 3: Melt the chocolate with the butter.
Step 4: Mix the flour, sugar, and egg yolks.
Step 5: Beat the egg whites until stiff. Add the chocolate and melted butter to the flour, sugar, and egg yolk mixture.
Fold in the egg whites until you have a smooth mixture.
Step 6: Pour the mixture into the circles of the pastry case. Bake for 20 minutes. Let cool, then remove from the mold and sprinkle with powdered sugar.