Wilt onions, peppers and celery in butter (do not brown). Remove from heat, add remaining ingredients except cracker crumbs.
Gradually add milk to flour, salt and pepper. Stir until smooth. Cook in double boiler until thick. Remove from fire and add butter. Add cream sauce to crawfish meat, place all in baking dish. Cover with cracker crumbs. Bake at 325F for 20 to 25 minutes.
Cajun Country -- New Iberia, Louisiana