Combine the pork and onion in a large skillet with enough water to cover; simmer over medium heat for 1 hour. Stir in the cloves, cinnamon, and walnuts; season with salt and pepper. Fold the crushed crackers into the mixture. Transfer to a covered casserole dish.
Preheat an oven to 350 degrees F (175 degrees C).
Bake stuffing in the preheated oven for 20 minutes; serve immediately.