Add 4 1/2 Tbsp salt to boiling water. Add cauliflower to salted water. Bring to a boil; cover. Simmer 12 minutes or until cauliflower is tender. Drain. Place 1 1/2 gallons cauliflower in each pan.
Blend butter or margarine and flour together, stirring until smooth. Add roux to milk, stirring constantly. Simmer 5 minutes or until thickened. Season with 2 Tbsp salt as needed. Add cheese; stir until blended.
Pour 2 1/2 quarts sauce over cauliflower in each pan.
Mix crumbs and butter or margarine. Sprinkle over cauliflower.
Preheat oven to 350° F. Bake 15 minutes or until crumbs are browned.
Servings: 100 - 1/2 cup portions