Mix yeast, ¼cup lukewarm milk, ½tablespoon granulated sugar and 3tablespoons flour. Let this starter mixture rest for 10 minutes.
Mix remaining lukewarm milk, the egg yolks, salt, remaining granulated sugar and flour. Mix well and stir into the starter dough.
Add 4tablespoons melted butter, little by little, to the dough, kneading it in to make sure it is incorporated until dough becomes blistered and separates easily from hand or spoon. Let the dough rise for about 1 hour. Preheat oven to 375°F.
Sprinkle flour on a board. Put the dough on it and stretch it to a sheet ½inch thick. Cut the dough into rounds with a 1- to 1½-inch cookie cutter.
Butter a kugelhof mold 9inches in diameter and 4inches high. Sprinkle it with cake crumbs. Dip the little dough rounds into remaining melted butter, and place a layer of them tightly on the bottom of the mold. Sprinkle with a mixture of walnuts and lemon rind.
Arrange more buttered dough rounds to make a second layer. Put ½teaspoon jam in the center of each round. Continue this way, alternating rounds with ground walnuts and rounds with jam until the mold is filled. Cover top with remaining melted butter. You may need up to ¼pound additional butter at this point.
Bake in the preheated oven for 35 to 40 minutes. Turn out of the mold, sprinkle with vanilla sugar, and serve with Wine Cream or Milk and Rum Cream.