In the bowl of a stand mixer, add yeast, lukewarm milk and honey. Let it sit for 15 minutes or until foamy. Meanwhile, in a medium bowl, add 2 cups flour (reserve ¾ cup on the side), garlic powder and salt; whisk until well combined and set aside.
Add unsalted butter, egg and ¼ cup Parmesan cheese to the yeast mixture. Using a dough hook attachment, mix the ingredients well.
Add the flour mixture and process on low speed for 3 minutes.
Add 1 tbsp. reserved flour at a time to the bowl, mixing well after each addition, until the dough clings around the hook and pulls away from the sides.
Increase the speed to 4 and knead for 4 minutes.
With oily hands, form dough into a ball by pulling under and transfer to a lightly greased bowl with olive oil. Cover loosely with a clean dish towel and let rise in a warm, draft-free spot like the oven (temperature off) until it doubles in size, about 1 ½ hours. When rising time is up, punch dough and transfer to a lightly floured work surface. Sprinkle flour on the dough and form a ball by pulling under.
Using a bench scrapper, cut the dough ball in half (sprinkle on more flour if needed) and cut each half in half. Form a ball with each piece.
Cut each ball in half and each of them in half again, pulling under and forming a ball; repeat. In total, 32 balls are needed for this recipe.
Preheat oven to 375ºF.
Place a small ramekin dish upside down in the center of a lightly greased 12-inch deep dish pizza pan; set aside.
Working with one ball at a time, flatten it out to about 2 ½-inches around and place a piece of mozzarella cheese in the center followed with a small piece of hard garlic butter. Gather the edges together making sure the stuffing mixture is well covered and tightly pinch it closed.
Transfer to the prepared pizza pan, leaving a small space in between. Cover and let it proof for 30 minutes.
In a small bowl, combine egg and milk; beat well and set aside.
Brush the egg wash on the dough balls after the rising time is up.
Transfer to the preheated oven and bake for 30 minutes.
Meanwhile, melt the rest of the garlic butter.
Remove from the heat and brush on a generous amount of melted butter. Evenly sprinkle on the remaining ¼ cup of Parmesan cheese.
Return to the oven and bake for 3 minutes or until the cheese is somewhat melted.