Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper. Lightly grease with cooking spray or olive oil.
In a mixing bowl, combine the shredded mozzarella cheese, grated Parmesan cheese, and all-purpose flour. Mix well until the ingredients are evenly distributed.
In a separate bowl, whisk the egg, garlic powder, salt, and black pepper. Add the egg mixture to the cheese and flour mixture, then stir until a dough forms. If using, fold in the chopped parsley for added flavor.
Using your hands, form small bite-sized balls of dough (about 1 inch in diameter) and place them evenly on the prepared baking sheet.
Bake in the preheated oven for 15-20 minutes, or until the bites are golden brown and the cheese is bubbly.
Remove from the oven and let them cool slightly before serving. Enjoy your cheesy bites warm!