In a medium sized skillet on the stove-top, brown and crumble the Italian sausage until it is no longer pink. Drain off excess fat and allow the sausage to drain further on several layers of paper towels.
Prepare the zucchini by cutting it in half lengthwise and then scooping out the seeds with a spoon.
Divide the Italian sausage and pizza sauce evenly into the two zucchini boats.
Carefully place stuffed zucchini boats into the bottom of a 4 quart or larger slow cooker.
Cover and cook on LOW for 3 to 4 hours.
Turn slow cooker off and sprinkle the mozzarella cheese on top of each zucchini boat. Recover and allow the cheese to melt for 10 to 15 minutes in the warm slow cooker.
Feel free to add more of your favorite pizza toppings to the zucchini boats, sliced pepperoni, olives, Canadian bacon, mushrooms, peppers are all great options!