Add sausage to a medium skillet and cook until browned. (It does not need to be cooked through, just browned on the outside for extra flavor. You can skip this step if you do not have time.)
Add browned sausage, along with the rest of the ingredients to a slow cooker.
Cook sauce on low for 8 hours.
Serve over pasta with basil and parmesan cheese for serving, if desired.