Preheat the oven to 350 degrees F.

In a large skillet brown the Italian sausage and drain off any fat. Add the thinly sliced zucchini and spaghetti squash noodles and cook over medium low heat for 5 minutes, stirring occasionally. This will help soften the zucchini and cook off any moisture remaining in the spaghetti squash.

Add the drained tomatoes and low carb marinara, then pour into a greased 7x11 baking dish.

In a small bowl combine the cream cheese, sour cream, garlic, Italian seasoning and parmesan. Carefully spread over the sausage mixture. Top with the shredded mozzarella.

Bake for 25-30 minutes until the cheese has begun to brown. Allow the casserole to rest at least 5 minutes before serving.