Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper or lightly grease it with cooking spray or olive oil.
In a mixing bowl, combine the grated Parmesan cheese, shredded mozzarella cheese, breadcrumbs, garlic powder, onion powder, black pepper, and chopped parsley if using. Mix well to distribute all ingredients evenly.
In a separate small bowl, beat the egg. Add the beaten egg to the cheese mixture and stir until everything is well combined.
Using a spoon, scoop out small amounts of the mixture and shape them into bite-sized balls, about the size of a golf ball.
Place the cheese bites on the prepared baking sheet about an inch apart. Optionally, brush the tops lightly with olive oil for extra crispiness.
Bake in the preheated oven for about 10-15 minutes, or until the cheese bites are golden brown and crispy on the outside.
Remove from the oven and let them cool slightly before serving.