Cook spaghetti pasta according to package instructions until al dente. Drain and set aside.
In a large skillet, sauté the diced onion and green bell pepper over medium heat until softened, about 5 minutes.
Add the minced garlic and cook for another minute until fragrant.
Add ground beef to the skillet and cook, breaking it up with a spoon, until browned and cooked through, about 7-10 minutes.
Drain excess fat if necessary.
Stir in diced tomatoes, tomato sauce, chili powder, Worcestershire sauce, salt, and black pepper.
Bring the sauce to a simmer and cook for 10 minutes, allowing flavors to meld and sauce to thicken slightly.
Add cooked spaghetti to the skillet and toss gently to coat pasta evenly with the sauce.
Serve pasta twirled into a mound on plates, topped with a generous sprinkle of shredded cheddar cheese.