Prepare celery and cook as for boiled celery.
Drain and lay in shallow oven dish.
Slice and saute mushrooms, in oil, and lay them over the celery.
Make white sauce, flavour with little apple juice and season well.
Pour over the celery and mushrooms but do not cover the vegetables.
Sprinkle with grated cheese and bake or put under the grill until lightly browned.