Preheat the oven to 400 degrees Fahrenheit and line a baking sheet with foil or parchment paper.
In a large mixing bowl, combine pound lean ground beef, beaten egg, plain breadcrumbs, grated Parmesan cheese, garlic powder, Italian seasoning, salt, black pepper, and chopped fresh parsley.
Mix gently with your hands or a wooden spoon until just combined. Do not overmix.
Take approximately of the meat mixture. Roll it into a ball and place a piece of the cheese into the center of the ball.
Place the prepared meatball on the baking sheet. Continue this process until all the meat mixture and cheese are used.
Bake for 15-20 minutes (flipping halfway) until the meatballs are no longer pink in the center. Watch them closely so that the cheese does not spill out while they are cooking.
Heat the marinara sauce in a small saucepan.
Serve the meatballs topped with the marinara sauce and enjoy!
Notes
Refrigerate the leftovers in an airtight container for up to 5-7 days.