Preheat oven to 375°F (190°C).

Bring a large pot of salted water to a boil and cook macaroni for 2 minutes less than the package directions for al dente; drain and set aside.

In a large skillet over medium-high heat, brown the ground beef and diced onions until the meat is thoroughly cooked through.

Add minced garlic to the skillet and sauté for 60 seconds until fragrant.

Drain the rendered fat from the skillet.

Stir in the tomato sauce, diced tomatoes, Italian seasoning, salt, and pepper; simmer for 5 minutes.

Combine the cooked macaroni and the meat sauce in a 9x13 inch baking dish and stir until evenly incorporated.

Top the mixture with the shredded cheddar cheese.

Bake for 15 to 20 minutes until the cheese is melted and the edges are bubbling.

Allow the casserole to rest for 5 minutes before serving.