Layer vegetables, beginning with the layer of Ritz crackers on the bottom of the casserole. Combine celery soup and sour cream. Place on top of layered vegetables. Add cheese next. Melt butter. Place Ritz crackers on top and pour melted butter over the crackers.
Bake at 350 degrees for 30 minutes covered. Uncover in the last 5 minutes of cooking to allow to brown.
