Cook the cauliflower in salted water for 10 - 12 minutes, depending on the firmness you want.
In the meantime, melt the butter and stir in the flour with the whisk until it has a creamy consistency. Then gradually add the milk. Keep stirring. When everything is well mixed, add approx. 100 ml of the cauliflower water and season to taste with the spices. Simmer over a low heat for about 10 minutes. Finally add the cauliflower.