8: ...and mix thoroughly with a whisk. Keep stirring until the bechamel thickens. Check the seasoning.
9: Add 80 g Parmesan (Parmigiano Reggiano)...
10: ...and stir until the cheese has melted. Your Parmesan and cauliflower-flavoured bechamel is ready.
11: Pour a generous amount of sauce over the cauliflower.
12: Scatter a little more Parmesan over, or use a different cheese for the topping, such as Comté, Emmental, Cheddar...
13: Bake for about 30 minutes. As always with gratin-style dishes, you can finish with a quick blast under the grill for 2 or 3 minutes to brown the top.
Remarks
You may well have some sauce left over after stage 11. This can be kept in the fridge for several days in a sealed container.