Heat the saucepan on medium heat and melt the butter.
Add the flour and mix with the whisk until the mixture is homogenised. Continue stirring until the flour is slightly browned, for about 5 minutes.
Add lukewarm milk and continue stirring with the whisk until the ingredients are well homogenized. Once it starts boiling, reduce heat, salt and simmer for about 20 minutes, stirring frequently with a spoon, so that the sauce does not stick to the bottom of the saucepan. Strain the sauce in the chinois, try it in order to add salt, cool it quickly and keep it in the refrigerator.
TIPS
* The butter-flour blend is called roux in French and is one of the main congealing mixtures used in cooking. Depending on the amount of “roux” you use, you determine the density of béchamel: the use of less amount has a thinner result, while the use of a larger amount has a thicker result.
* You can enrich the taste of the béchamel by adding different kinds of cheese (parmesan, graviera, feta etc.).
* When you want to roast the béchamel sauce in recipes such as moussaka, add some egg yolks to it.
