Place first 6 ingredients into a 5-6 qt slow cooker and stir. Turn the slow cooker on low and cook for 6-8 hours.
Stir and then add the cooked spaghetti, allowing the spaghetti to heat through (about 30 minutes).
*Optional ingredients: 1 (4 oz) can sliced, black olives, 1 (4 oz) can sliced mushrooms and/or 1 small onion, diced. If you choose to add any of these, add them at the beginning with the other first 6 ingredients.
**I have made this on the stove top with good results. Adding the first 6 ingredients to a 5-6 qt pot (dutch oven), allowing it to heat on medium until the cheese melts (15 minutes) and then turning the heat down to low and adding the cooked spaghetti, until it too, is heated through (30 minutes).
***I have also made this for OAMC as it heats up well!