Preheat oven to 450.
Make a bachamel sauce, 2 cups (2 tbsp butter, 2 tbsp flour, 2c. milk).
Add 2 cups of gruyere or fontina, 1/2 tsp dijon mustard, 1/2 tsp worcestershire sauce, and a pinch of cayenne powder.
On a rimmed baking sheet, toss 1 head of cauliflower florets with 3 tbsp olive oil (season with salt/pepper). Roast until tender, stir after 10 minutes.
Top with cheese sauce.