In a large skillet, cook the ground beef over medium heat until browned, breaking it up with a spoon as it cooks.

Drain any excess grease.

Add the diced onion, green bell peppers, and minced garlic to the skillet with the beef. Sauté for 3-4 minutes, or until the vegetables are softened and fragrant.

Stir in the crushed tomatoes, tomato paste, water, oregano, basil, sugar, salt, and black pepper. Reduce the heat to low and let the sauce simmer for 20-25 minutes, stirring occasionally.

While the sauce simmers, bring a large pot of salted water to a boil. Cook the spaghetti according to package instructions until al dente. Drain and set aside.

Toss the cooked spaghetti with the meat sauce until fully coated. Serve immediately, topped with grated Parmesan cheese and fresh parsley, if desired.