Lightly brush a 3 1/2-quart slow cooker with melted butter. Add pear, oats, raisins, brown sugar, 3 Tbsp. honey, 2 Tbsp. melted butter, salt, cinnamon and nutmeg. Stir in milk and boiling water. Cover and cook on low for 7 hours or until oats are tender. Serve drizzled with more honey if desired and topped with chopped toasted walnuts.