Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper.
In a large mixing bowl, whisk together the flour, baking powder, salt, and black pepper.
Add the cold, cubed butter to the flour mixture. Use a pastry cutter or your fingers to cut the butter into the flour until the mixture resembles coarse crumbs.
Gradually pour in the milk, stirring until just combined. Do not overmix; it's okay if there are a few lumps.
On a floured surface, gently roll out the dough into a 1/2 inch thick rectangle.
In a separate bowl, mix the shredded mozzarella, grated Parmesan, garlic powder, and chopped parsley.
Cut the dough into squares (approximately 3x3 inches). Place a generous spoonful of the cheese mixture in the center of each square.
Fold the corners of the dough over the filling to form a pocket and seal well. Place the stuffed biscuits seam-side down on the prepared baking sheet.
Brush the tops of the biscuits with melted butter to ensure a golden finish.
Bake for 15-18 minutes or until the biscuits are puffed and golden brown.
Once out of the oven, let them cool slightly. Brush with additional melted butter and sprinkle with extra parsley for garnish.