Melt the butter in a medium saucepan over medium heat. Stir in the apple, onion, celery, and walnuts, and cook 5 minutes, until vegetables are tender. Mix in the applesauce, water, and breadcrumbs. Cook and stir until the breadcrumbs have absorbed the liquid. Season with cinnamon, kosher salt, cloves, nutmeg, and ginger.
Unroll the pork roast, and place in a baking dish. Season with salt and pepper to taste. Spoon the stuffing mixture over the roast. Arrange any excess stuffing around the roast. Roll the roast so that the fatty side is on top, and tie with kitchen twine.
Bake 45 to 50 minutes in the preheated oven, to an internal temperature of 145 degrees F (63 degrees C).
