Layer cauliflower, pimento, green pepper, water chestnuts, eggs, onion and cheese in 2.5 quart casserole. Make sauce by melting butter and stirring in flour, salt and pepper. Cook and stir 1 minute. Add milk gradually. Add cheese and cook until thickened. Pour over vegetables. Combine topping ingredients; sprinkle over all. Bake at 180ÂșC or 30 minutes. Yield dozen servings.