Preheat oven to 350°. Cook spaghetti according to package directions. , In a 12-in. cast iron skillet, cook bacon over medium heat until crisp, stirring occasionally. Remove with a slotted spoon; drain on paper towels. Add beef and onion to drippings. Cook and stir until beef is no longer pink, 5-7 minutes, breaking meat into crumbles. Stir in tomato sauce, beans, diced tomatoes, chili powder, Worcestershire sauce, cumin, oregano and garlic powder. , Drain spaghetti; stir into skillet. Stir in 1-1/2 cups cheese and half the bacon. Top with remaining 1-1/2 cups cheese. Bake until heated through, 20-25 minutes. Sprinkle with green onions and remaining bacon.