Cook the chicken sausage in a large skillet set over medium heat, until crumbled and slightly browned. Add the garlic, onion and bell pepper if using and cook, stirring often, 3 to 4 minutes until the onion softens slightly.
Scrape the sausage mixture into the slow cooker. Add the tomatoes, tomato paste, sugar and seasonings. Stir to combine. (My crushed tomatoes were really thick, so I also added 1 cup of water.) Cover and cook on LOW for 6 to 8 hours.
Ideal Slow Cooker Size: 5 to 6-Quart. (I used my Instant pot.)
* Weight Watchers Friendly