The béchamel we all know is made of milk, flour and butter, a recipe which is its simplest and most common version these days.
Some more classic recipes suggest onion sautéed in the butter or even its addition in large chunks with 2-3 cloves pressed into each. Bay leaves and nutmeg can complete the picture.
Even older recipes suggest onion, carrot and celery as béchamel ingredients as well as pieces of fresh or cured-smoked meat to add flavor.
The simple version of the sauce we find these days is definitely more suitable for today’s applications. You mustn’t however forget that you can be flexible, depending on the occasion. In a vegetable gratin, the light aroma of smoked meats may be a pleasant surprise. You can also enhance the flavor of béchamel by adding various cheeses at the end of the cooking, such as parmesan, gruyere, cheddar, feta, etc.