1/4 oz. pkg. (2 1/2 tsp.) active dry yeast
3/4 c. (6 tbsp.) unsalted butter
1 1/4 c. milk
2 lg. eggs, unbeaten, plus 1 slightly beaten lg. egg
1/4 c. sugar
1 1/2 tsp. salt
5 - 5 1/2 c. unbleached all purpose flour
1 lb. whole milk Mozzarella, diced into 1/4" cubes
1 lb. brick or Muenster, diced into 1/4" cubes

In a large bowl proof the yeast in 1/4 cup lukewarm water for 5 minutes, or until foamy. In a small saucepan, melt the butter, add the milk and heat the mixture until lukewarm. Stir the milk mixture into the yeast mixture, add the unbeaten eggs, sugar and salt, combining the mixture well and stir in 4 cups of flour. Add 1 cup of the remaining flour, combine the dough well, and add enough of the remaining 1/2 cup flour to form a soft but smooth and elastic dough.

Knead the dough on a lightly floured surface for 3 minutes, form it into a ball and put it in a lightly buttered bowl, turning it to coat it with butter. Let the dough rise, covered, in a warm place for 2 hours, punch it down and let it rise again, covered, for 1 hour. Halve the dough and form the halves into balls. Place the halves in lightly buttered bowls, turning them to coat them with butter and let the dough rise, covered in a warm place for 1 hour.

On a work surface roll out 1 ball of dough into an approximate 16"x13" oval. Sprinkle half of the Mozzarella and half of the brick cheese on a lengthwise half of the dough. Fold the other half over the cheeses and seal the edges well, pinching them together.

Transfer the dough to 1/2 of a large buttered baking sheet, prick the top all over with a fork, and brush it lightly with half of the beaten egg. Make the second loaf with the remaining dough and cheeses in the same manner and transfer it to the other half of the baking sheet. Prick the top of the dough all over with a fork and brush it lightly with the remaining beaten egg.

Bake the breads in the middle of a preheated 400 degree oven for 20 to 25 minutes or until they are golden brown. Makes 2 loaves.