Brown the beef: Heat a large skillet over medium-high heat. Add ground beef and cook for 5-7 minutes until browned. Drain excess fat.

Sauté aromatics: Add diced onion and minced garlic to skillet. Cook for 2-3 minutes until onion is translucent and garlic is fragrant.

Combine ingredients: Stir in tomato sauce, diced tomatoes, Italian seasoning, salt, and black pepper into the beef mixture. Simmer for 5 minutes.

Cook pasta: Boil salted water and add elbow macaroni. Cook 8-10 minutes until al dente. Drain and set aside.

Mix elements together: In a mixing bowl, combine cooked macaroni, beef mixture, cheddar cheese, mozzarella cheese, and sour cream. Stir well.

Layer and bake: Transfer mixture into a greased baking dish. Top with Parmesan cheese. Preheat oven to 375°F and bake for 25-30 minutes.

Cool and serve: Let casserole cool for 5 minutes, then serve.