Preheat oven to 350ºF. Heat oil in large skillet on medium heat. Add celery; cook and stir 5 min. or until crisp-tender. Stir in water. Bring to boil. Remove from heat. Stir in stuffing mix, cranberries and walnuts. Add 1/2 cup of the cheese and the egg; mix lightly.
Spoon stuffing mixture evenly into eight greased medium muffin cups, mounding mixture as necessary to use all the stuffing mixture. Sprinkle with remaining 1/2 cup cheese.
Bake 10 min. or until stuffing cups are heated through and cheese is melted.