1Cook and drain spaghetti as directed on package; cover to keep warm.
2Meanwhile, in 12-inch skillet, heat oil over medium heat. Cook onion and bell pepper in oil 3 to 4 minutes, stirring occasionally, until tender. Remove from skillet. Add beef to same skillet. Cook 8 to 10 minutes, stirring frequently, until thoroughly cooked; drain.
3Add onion and bell pepper to beef; mix well. Stir in sugar, taco seasoning mix, tomatoes, tomato sauce, corn and mushrooms. Heat to boiling. Reduce heat to low; simmer 5 minutes, stirring occasionally. Serve over spaghetti. Sprinkle with cheese.