Preheat the oven to 350°F (175°C).
Cook the egg noodles according to package instructions until al dente. Drain and set aside.
In a large skillet, heat olive oil over medium heat.
Add diced onion and cook for 3-4 minutes until softened.
Add minced garlic and cook for 1 minute until fragrant.
Add ground beef to the skillet and cook until browned, breaking it apart with a spoon, about 6-8 minutes.
Drain excess fat from the skillet.
Stir in tomato sauce, diced tomatoes, dried Italian seasoning, salt, and black pepper. Simmer for 5 minutes to combine flavors.
In a large mixing bowl, combine cooked egg noodles and the ground beef tomato mixture. Stir well to combine.
Transfer half of the noodle and beef mixture to a 9×13-inch baking dish.
Sprinkle half of the shredded cheddar and mozzarella cheese evenly over the layer.
Add the remaining noodle and beef mixture on top, spreading evenly.
Sprinkle the remaining shredded cheddar and mozzarella cheese over the top layer.
Cover the baking dish with aluminum foil and bake for 25 minutes.
Remove the foil and bake for an additional 10-15 minutes until the cheese is melted and bubbly.
Let the casserole cool for 5 minutes before serving.