For the domino slices, mix flour, dry yeast, baking powder, margarine, vanilla sugar, salt and knead a dough with egg and milk. Divide dough into 3 parts and roll out. Mix walnuts and granulated sugar.
Put the first half of the dough in a baking tray and spread it with jam, spread half of the walnut-sugar mixture over it and put the second half of the dough over it and again spread it with jam and spread the remaining walnut-sugar mixture over it and finally put the third half of the dough over it.
Bake at 180 °C. When the domino slices have cooled, glaze with chocolate icing. Cut into slices and, if desired, pipe domino patterns on them with egg white icing.