Heat nonstick skillet over medium-high heat. Brown sausage in nonstick skillet in batches. As a batch is finished browning on all sides, cut into 1½-inch chunks. Then place in slow cooker.
Slice or chop peppers and onion and put on top of sausage.
Add spaghetti sauce over all.
Cover and cook on Low 6 hours, or on High 3 hours.