Separate eggs. Beat egg whites with sugar and vanilla sugar for 3 min until creamy. Fold in yolks.
Mix flour, cornstarch and baking powder and sift over the dough. Gently fold in gradually with a whisk.
Cover a baking tray with parchment paper and smooth out the sponge mixture.
Bake in the heated oven at 200 °C (hot air 180 °C) for about 15 minutes on the middle shelf.
Sprinkle a thin layer of sugar on a piece of paper and turn the sponge out onto it. Remove the paper, cool the sponge and turn it to the other side. Cut into 7 x 3 cm rectangles.
Cut each rectangle in half diagonally and fill.
Melt light and dark cooking chocolate in a hot water bath. Cover one half of each rectangle with white cooking chocolate and one with dark cooking chocolate. Dry. Drizzle dark dots on the white half to make a domino game.
Tip: Feel free to use better chocolate – the more delicious the result!