In a large skillet cook the Johnsonville(R) Mild Italian Ground Sausage, onion, and garlic until meat is brown. Drain off fat.
In a 3-1/2- or 4-quart slow cooker combine Classico(R) Tomato and Basil pasta sauce, mushrooms, pepperoni, and basil. Stir in the sausage mixture.
Cover and cook on low-heat setting for 3 hours. If desired, stir in ripe olives and sweet pepper; cover and cook for 15 minutes more. To serve, spear the dippers with fondue forks and dip into the fondue.