Makes 2 medium-sized loaves.
2 packages (2 Tbs.) dry yeast
1 cup warm water
2 Tbs. sugar
5½ to 6½ cups white flour
1 cup milk
1 Tbs. salt
3 Tbs. butter, melted
1 egg yolk
1 Tbs. milk
Dissolve the yeast in the warm water and stir in 1 tablespoon of the sugar and 1¾ to 2 cups flour, enough to make a soft, spongy dough. Cover the bowl with a towel and put the sponge aside in a warm place to rise for about 45 minutes, or until it is puffed and soft.
Add the milk, the remaining sugar, the salt, and the melted butter, and stir the sponge down well. Work in as much of the remaining flour as is needed to make a fairly stiff dough. Turn the dough out onto a heavily floured board, sprinkle a little more flour over it, and knead it for 10 to 15 minutes, or until it is smooth and elastic; add flour as needed to keep the dough from sticking.
Form the dough into a ball and put it in a large, buttered bowl, turning it over once so that it is coated with butter on all sides. Cover the bowl with a light towel and put it in a warm, draft-free place for about 45 minutes to 1 hour, or until the dough has doubled in size.
Punch down the dough and form it into 2 oblong loaves or large braids. Put the loaves on buttered baking sheets, cover them with a light towel, and leave them in a warm place to rise for about ½ hour, or until they have nearly doubled in size.
Beat together the egg yolk and the tablespoon of milk and brush the loaves delicately with the glaze. Put them in a preheated 425 degree oven and after 5 minutes lower the heat to 375 degrees. Bake the loaves for 35 to 40 minutes more, until they are golden brown.
Cool the loaves on racks before slicing.