Melt the butter in a saucepan. Then add the flour and sweat it.
In a separate pot, boil the milk with the spices and the finely chopped onions for 5 minutes, then strain through a sieve.
Bring the butter-flour mixture to the boil with the milk and cook for 5 minutes, stirring constantly with a whisk.
Ready is the bechamel sauce and can be used for further cooking for example lasagna or with cooked vegetables.
Preparation Tip:
For a lasagna, prepare the bechamel sauce with a liter of milk (double the amount of ingredients).