Prepare the oven and baking dish. Preheat your oven to 400°F. Spray a 9x13-inch baking dish with nonstick cooking spray.

Brown the ground beef. While the noodles cook, add the ground beef to a large skillet. Cook until browned and fully cooked, breaking it into small pieces as it cooks. Drain the excess grease.

Add the onion and garlic. Stir in the diced onion and cook for 2–3 minutes until softened. Add the minced garlic and cook for another minute.

Make the tomato sauce mixture. Add the tomato sauce, drained diced tomatoes, Italian seasoning, salt, and pepper. Stir everything together.

Combine with the noodles. Add the cooked and drained egg noodles to the skillet. Mix until the noodles are evenly coated with the beef and tomato sauce.

Layer the casserole. Spread half of the noodle mixture into the prepared baking dish. Sprinkle half of the shredded cheddar cheese over the top. Add the remaining noodle mixture and finish with the rest of the cheese.

Bake. Place the dish in the oven and bake for 10–15 minutes, or until the cheese is melted and the casserole is heated through.

Serve. Let the casserole rest for a few minutes before serving. Spoon it onto plates and enjoy while the cheese is still warm.