Wash cauliflower and separate into flowerets.
Place flowerets and water in a deep, 1 1/2-quart, heat- resistant, non-metallic casserole.
Heat, covered, in Microwave Oven 7 to 9 minutes. Set aside.
In a medium-sized, heat-resistant, non-metallic bowl melt butter, uncovered, in Microwave Oven 15 seconds.
Blend in flour and salt. Stir till smooth. Gradually add milk.
Heat, uncovered, in Microwave Oven for 1 minute. Stir. Heat an additional 1 1/2 minutes or until sauce is thickened and smooth. Stir occasionally.
Stir grated cheese into sauce.
Pour sauce over cauliflower and heat, uncovered, in Micro- wave Oven 1 minute or until cauliflower is heated through.
Sprinkle paprika over sauce before serving.