Cut the tops off the peppers. Remove the stem from the top and chop the rest. Pull the seeds and ribs from the pepper and discard. Reserve the pepper shells.
In a big skillet, brown and crumble the sausage till done.
Run the cauliflower through the shredding blade of a food processor. Place the cauli-rice in a big mixing bowl.
Put 1 cup of the spaghetti sauce in the bottom of the slow cooker. Add the rest to the bowl with the cauli-rice. Add the cheese, onion, tomato, parsley, olives, garlic, salt, Italian seasoning, cooked sausage, and the chopped bit of pepper to the bowl. Combine well. Divide the mixture between the pepper shells.
Put the pepper shells in the slow cooker. Cover, set it to low, and let it cook 4-5 hours or until the peppers are tender.