To make the béchamel, heat a saucepan over medium heat and melt the butter. Once melted, add the flour to create a roux and stir until smooth. Cook for about 6 to 7 minutes, stirring frequently, until it turns a light-golden brown.
Meanwhile, in a separate pot or in the microwave, heat the milk to just under a boil.
Once done, remove from the heat and season with the salt and if using in an Italian dish, freshly-grated nutmeg.