If refrigerated chopped butternut squash is not available, use 1 12-ounce package frozen chopped butternut squash. Another small pasta (macaroni, orzo or small shells) may be used in place of ditalini.
Spray the inside of 4-quart slow cooker with the cooking spray. Add the tomato sauce, water, squash and garlic powder to the slow cooker; stir to combine. Pinch the sausage into bite-size pieces and place in the slow cooker. Cover; cook on low for 7½ hours or on high for 3½ hours.
Stir in the pasta and spinach; cover and cook on high 30 minutes more or until the pasta is tender.