1Preheat your oven to 375°F (190°C).
In a large mixing bowl, combine the ground beef, Italian breadcrumbs, marinara sauce, egg, grated Parmesan cheese, chopped onion, garlic powder, and black pepper.
Mix all the ingredients together until well combined.
Transfer the mixture to a loaf pan and shape it into a loaf.
Bake in the preheated oven for 45-50 minutes, or until the meatloaf is cooked through and reaches an internal temperature of 160°F (71°C).
Let the meatloaf rest for 10 minutes before slicing and serving.