In a 3-1/2- to 4-1/2-quart electric crockery cooker place the onions and garlic. Add chicken to cooker.
In a mixing bowl combine undrained tomatoes, tomato paste, vinegar, bay leaves, sugar, rosemary, salt, and pepper; mix well. Pour over chicken.
Cover and cook on low-heat setting for 7 hours. (Or, cook on high-heat setting for 3-1/2 hours.)
When ready to serve, remove bay leaves. Stir mushrooms into chicken mixture; cook for 5 to 10 minutes more to heat through. Meanwhile, cook pasta according to package directions. Serve the chicken and sauce over the hot cooked pasta; sprinkle with Parmesan cheese. Makes 4 main-dish servings.