Cook the cauliflower whole in 1/4 cup water in the microwave for 8 minutes or on top of the stove until tender.

SAUCE:

1/2 c. mayonnaise
2 tsp. dry mustard
1/2 tsp. minced dry onion

Mix and spread over cauliflower. Lay 3 slices of yellow cheese on top. Return to the microwave for 1 minute on high or heat in the oven at 350 degrees until the cheese melts.