Stuffed shells are a classic Italian dish, and this innovative vegetarian version is filled with a delicious mixture of spinach and ricotta cheese. The jumbo pasta shells are cooked until al dente, then stuffed with a mixture of sautéed spinach, ricotta cheese, Parmesan cheese, and herbs. The shells are then baked in marinara sauce until bubbly and golden. Serve them as a main course with a side salad for a satisfying and flavorful meal.