In a large skillet, cook bacon over medium heat until crisp. Remove to paper towels; drain, reserving one tablespoon of drippings. Set bacon aside for later use.
In the same skillet, cook beef and sausage over medium heat for 8-10 minutes or until no longer pink, breaking into crumbles; drain if necessary and set aside.
Heat oil in the same skillet; add onion and sauté until tender, about 5 minutes. Stir in tomato paste; cook and stir for 1 minute more. Add remaining ingredients except for spaghetti and Parmesan cheese; mix well. Bring to a boil over medium-high heat; reduce heat to low and simmer uncovered for 30 minutes, stirring occasionally.
During the last 10 minutes of cooking, cook spaghetti according to package directions.
To serve, place cooked spaghetti onto individual plates; top with sauce and sprinkle with bacon and Parmesan cheese.