Knead all the dough ingredients together and press them into a greased dish, forming a 2-3 cm high rim. Mix together all the ingredients for the piebald and pour on the bottom. ATTENTION: Do not be confused that the mass is so thin. It gets stuck when you bake it! Bake the cake for approx. 45-50 minutes. Beat the egg whites with the sugar to form egg whites and place on the cake. Spread evenly. Bake for another 10-15 minutes. Use the chopstick sample to test whether the cake is through. Do not remove the cake from the pan until it has cooled down. If you are lucky, small sugar crystals will form and deposit on the cake. Looks like little gold pearls.