Bechamel is one of the most iconic and practical sauces available. Auguste Escoffier included it as one of the five"Mother Sauces" of French cuisine (Béchamel, Espagnole, Velouté, Hollandaise, Sauce tomate) in his famous book Le guide culinaire.
Before getting into the details, we need first to answer one important question: What is Bechamel? Bechamel is a sauce created mixing Roux (Fat+Flour) and Milk.
There are three ways you can flavour your bechamel: Flavour the butter before doing your roux, infuse the milk while heating it, or add extra ingredients/spices once the bechamel is cooked.
The most tradicional recipe of this sauce only infuses the milk with a bay leaf and onion as well as seasons it with a bit of nutmeg and salt. That would be the simplest, more classic way of cooking it, but this sauce accepts virtually any ingredient you could imagine.
Another dimension to this sauce appart from flavour is it's consistency. By adjusting the proportion of roux:milk you use, you could make your bechamel really thin or completely solid.
This open the possibility of using this sauce as an ingredient by itself. One example are croquetas; they are deep fried balls of thick bechamel, or savoury Soufflés, where the foundation of the dish is a thin bechamel which gets mixed with egg yolks and whisked whites.
Many other dishes uses bechamel as a sauce which joins together other ingredients; one example is Macarroni Cheese. A big proportion of grated dishes are fishined with a layer of bechamel which then gets brown under a grill.
It is fascinating the bast ammount of recipes that uses bechamel in some of it's forms. That's the reason why is quite important to practice and master this "Mother Sauce".
The first step for creating a bechamel is to warm your milk. It will be easier to incorporate into the flour if you do so. While heating it, add any extra ingredient you want to use to infuse your milk.
Next, put the butter in a pan on a low heat, so it melts. Once it is melt, add any ingredient of the bechamel that either requires cooking or can add flavour the butter.
Once the butter is nice and hot, add the flour and cook your roux at low heat until is golden.
Once ready, start pouring the milk in several batches. After each pour, make sure all the milk is incorporated before adding more.
After adding all the milk, you should end up with a nice bubbly bechamel. As the bechamel boils, it becomes thicker, so keep in mind what kind of texture you are looking for. Always use a low heat as at this stage is easy for the bechamel to get stick to the bottom of the pan.
Finally, you can add any cooked ingredient (cheese, cooked bacon, etc...) in order to add flavour and texture to your bechamel. Enjoy it while is warm!