Preheat the oven to 375°F (190°C).
Cook the elbow macaroni according to package instructions until al dente. Drain and set aside.
Heat olive oil in a large skillet over medium heat. Add diced onion and cook for 3-4 minutes until softened.
Add minced garlic to the skillet and cook for 1 minute until fragrant.
Add ground beef to the skillet and cook, breaking it apart with a spoon, until browned and cooked through, about 6-8 minutes. Drain excess fat if necessary.
Stir in the marinara sauce, diced tomatoes with their juice, dried Italian seasoning, salt, and black pepper. Simmer the sauce for 5 minutes.
In a large mixing bowl, combine the cooked macaroni and the meat sauce. Stir until well mixed.
Transfer the pasta mixture into a 9×13-inch baking dish. Sprinkle shredded mozzarella cheese evenly over the top.
Sprinkle grated Parmesan cheese over the mozzarella.
Bake in the preheated oven for 20 minutes, or until the cheese is melted and bubbly.
Remove from the oven and let it rest for 5 minutes before serving.