In a bowl, add flour and dry yeast, then sugar, salt, and butter. Add milk, and egg.
Mix with a wooden spoon until you have a dough with a thick, gooey consistency.
Sprinkle some flour on a cutting board, and drop the dough on to it. Turn it over a few times, and then knead, using fingers to fold and press the dough. The dough won't stick even without extra flour.
Place the dough on a baking tray. Cover until the dough has almost doubled in size.
Cut the Mozzarella cheese into slices.
Flatten the risen dough into a circle, and score it with evenly-spaced parallel lines across the surface of the dough, using a suitable blade or knife. Then score evenly-spaced parallel lines perpendicular to the first set of lines.
With a brush, apply egg wash to the edges of the dough.
Combine the garlic butter ingredients. Mix well.
Apply garlic butter over the whole surface of the dough, using a spoon. After the whole surface is covered with the garlic butter, use the edge of the spoon to enlarge the cracks created by the scoring.
Slice the Mozarella into narrower slices (about ¾ inches deep), and insert them, edgewise, into the cracks in the top of the dough in one direction. Then, using shorter slices, insert into the cracks perpendicular to the already filled cracks.
Apply freshly cracked pepper over the surface of the filled dough.
Bake dough in a 400°F preheated oven, top-bottom heat for 20 to 25 minutes. Ovens may vary.
Best eaten warm. Pull the bread apart into bite-sized pieces.