Mix warm water with egg whites, melted sugar, salt, butter and dry yeast in a baking bowl. Let stand for five minutes.
Put flour in a suitable bowl, mix with the yeast mixture to form a soft dough. Knead extensively on a floured board until completely smooth. Cover with plastic wrap and let rise until doubled in size.
Knead again. Divide into four portions and knead extensively. Roll out into round patties 3 mm thick.
Prick surface several times with a fork, brush with water and sprinkle with mixture of poppy seeds, sesame seeds and caraway seeds. Bake the patties on a greased baking tray in the oven heated to 180 °C for 10-15 min until golden brown.