Preheat oven to 375 ̊F and prepare a parchment-lined baking tray.
In a large bowl, combine ground beef, egg, garlic powder, Italian seasoning, salt and pepper, and mix thoroughly. Roll into balls and fill the centre of each meatball with 1 tbsp of mozzarella cheese. Place on baking tray and bake for 15-20 minutes or until fully cooked.
Once cooked, remove meatballs from baking tray and place into a large cast iron skillet. Pour
tomato sauce and top with Cheddar cheese. Place back into the oven and bake until cheese is gooey (5 minutes).
When cheese is melted, remove from heat, garnish with basil and serve.