Cook cauliflower in small amount of boiling salted water, cover until crisp-tender, drain well. Remove from pan. Melt 1/4 cup margarine or butter in same saucepan. Stir in flour. Add milk all at once. Cook and stir until mixture is very thick and begins to bubble. Add cheese and sour cream, cook and stir over low heat until cheese is melted.

Stir in ham, mushrooms and cooked vegetables. Turn into a 2 quart casserole. Combine bread crumbs and 1 tablespoon melted margarine or butter, sprinkle on top of casserole. Bake uncovered in a 350 degree oven for 40 minutes. Makes 6 servings.