Mix together about ¾ glass each warm milk, butter, and egg yolks, 1 spoon yeast, and 1¼ lbs flour. Knead the dough until it does not stick to your hands, place in a buttered napkin, and tie it up, leaving enough room for the dough to rise. Submerge the bundle of dough in cold water overnight. The next day, when the dough has risen to the surface, remove it from the napkin and knead it thoroughly, incorporating ⅓ glass sugar. Cover the dough and leave it on the table for an hour to rise slightly. Roll out a thin sheet of dough and place it on a baking sheet lined with paper. When it has risen slightly, paint with egg and dry out in the summer oven.