Cook the ground beef in a skillet over medium heat until browned, breaking it apart as it cooks. Drain excess grease.

Add diced onion, green bell peppers, and minced garlic. Sauté 3–4 minutes until softened.

Stir in crushed tomatoes, tomato paste, water, oregano, basil, sugar, salt, and pepper. Reduce heat and simmer 20–25 minutes, stirring occasionally.

Bring a large pot of salted water to a boil. Cook spaghetti according to package instructions until al dente. Drain.

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