In a large skillet, heat over medium heat and add 1 pound of ground beef. Brown the meat for about 5-7 minutes until it's well-cooked and no longer pink, breaking it apart with a spatula. Once done, drain any excess fat.

Add one diced onion and two cloves of minced garlic to the skillet with the cooked beef. Stir together and cook for 2-3 minutes until soft.

Incorporate 15 ounces of tomato sauce, one can of diced tomatoes, and a tablespoon of Italian seasoning into the beef mixture. Season with salt and pepper to taste. Let simmer for about 5 minutes.

Meanwhile, bring a pot of salted water to a boil and prepare 2 cups of elbow macaroni according to package instructions. Cook until al dente, about 8-10 minutes, then drain.

In a large mixing bowl, combine the drained macaroni with the beef mixture, 1 cup of shredded cheddar cheese, 1 cup of shredded mozzarella cheese, and ½ cup of sour cream. Mix thoroughly.

Preheat your oven to 350°F. Transfer half of the mixture to a greased 9x13-inch baking dish, top with half the remaining cheese, followed by the rest of the meat mixture and the final layer of cheese.

Cover the baking dish with foil and place it in the preheated oven. Bake for 20 minutes, then remove the foil and continue baking for an additional 10-15 minutes until bubbly and golden brown.

Remove from the oven and let cool for 5 minutes before serving.