Directions

• Sprinkle yeast over warm water; stir in 1 TBSP flour. Let stand until creamy (about 5 minutes).
• Stir together salt and remining flour in large bowl; then stir in egg and yeast mixture to form a dough.
• Turn out dough onto well-floured surface. Turn to coat with flour, then knead until smooth and elastic (about 5 minutes). Form into a ball; dust with flour. Let dough rest in a plastic-covered bowl, punching down with a wet fist every hour, for at least 2 hours, up to 3 hours.
• Preheat oven to 500 F with rack in middle.
• Turn out dough onto flour pizza pan, turning to coat, then flatten with fingers into a 7-inch disk,
• Toss cheeses together and press into a compact 3-inch ball with hands. Place ball into middle of dough, gather dough up around cheese, squeezing extra dough into a topknot. Press down on topknot with damp fist to press cheese out from center. Continue to flatten dough and distribute cheese evenly, pressing outward from center, until dough is an 11-inch disk.
• Cut a 6-inch "X" through top of dough to expose cheese. Bake until pale golden, 10-12 minutes. Brush surface of dough with butter and bake until golden and cooked through, about 4-5 minutes longer.
• Cool slightly. Serve cut into wedges.