Prepare Bechamel. In a thick bottomed sauce pan, melt 3 tbsp. butter. Once butter is melted add 3 mounded tbsp. of white flour and whisk into paste or loose batter. This is the roux. After cooking the roux for a few minutes, add 2 cups whole milk, 1/8 tsp. of freshly grated nutmeg, 1/4 tsp. salt, and a dash of pepper. Whisk until sauce becomes thick and coats the back of a spoon.
In a bowl, toss steamed cauliflower and all of the Bechamel. Pour into prepared baking dish.
Sprinkle with cheese and place beneath a broiler for approximately 10 minutes (or until a golden crust forms)