Preheat your oven to 375°F (190°C) and grease a 9x13-inch baking dish.

Cook the ground beef in a large skillet over medium heat until browned, about 5–7 minutes, then drain excess fat.

Sauté the diced onion and minced garlic with the beef for 2–3 minutes until the onion is translucent.

Stir in tomato sauce, undrained diced tomatoes, Italian seasoning, salt, and black pepper, and let simmer for 5 minutes.

Boil salted water and cook elbow macaroni according to package instructions until al dente, then drain.

In a mixing bowl, combine the cooked macaroni, beef mixture, cheddar cheese, mozzarella cheese, and sour cream.

Transfer the mixture into the greased baking dish and top with grated Parmesan cheese.

Bake for 25–30 minutes until the top is bubbly and golden brown.

Let the casserole cool for 5 minutes before serving.