Place cauliflower on a paper plate. Cover with waxed paper. Microwave on high for 9 to 10 minutes. Mix 1 teaspoon brown mustard with 1 teaspoon mayonnaise and spread on cauliflower. Sprinkle with shredded Cheddar cheese and heat just enough to melt the cheese. (I usually cut my cauliflower first and put it in a dish to microwave. I then follow the rest of the recipe.)