Melt remaining 6 tablespoons butter in the same skillet. Add onion and cook for 3 to 4 minutes until almost tender, stirring frequently.
Spray a 4 to 6 quart slow cooker with nonstick cooking spray and place stuffing cubes in prepared crockpot. Add cooked onion with butter and mix gently. Add applesauce and water and mix lightly.
Cover and cook on low for 4 to 5 hours. Sprinkle with toasted walnuts before serving.
10 3/4 cup servings.