Preheat the oven to 375°F. Bring a large pot of salted water to a boil.
Cook noodles for ¾ of the time directed on the package, they should be slightly under al dente—tender on the outside but firm in the center. Drain and rinse under cold water.
Meanwhile, in a large skillet over medium-high heat, brown the beef, breaking it up as it cooks. Drain any grease.
Add the onion and garlic and cook until soft, about 4 minutes. Stir in the green bell pepper and cook 3 minutes more, stirring often.
Add the pasta sauce, diced tomatoes (with their juices), tomato paste, oregano, basil, salt, and pepper to the pan. Stir to combine, then bring the mixture to a boil. Reduce the heat and let it simmer for 5 minutes.
Combine the drained pasta, tomato meat sauce, and 1 cup of cheddar cheese in a 9×13-inch casserole dish.
Bake uncovered for 20 minutes. Top with the remaining cheeses (cheddar & mozzarella) and bake for an additional 10-15 minutes or until bubbly and browned.