Béchamel

Melt butter in a heavy saucepan over medium-low heat. Stir in all purpose flour and cook, stirring all the time, for 2 minutes. It should bubble and smell of biscuits without turning brown.

Pour about a third of whole milk into the roux and whisk hard until smooth. Add the rest in two more parts, whisking after each.

Bring the white sauce to a gentle simmer, whisking often and scraping the corners, and cook until it coats the back of a spoon. Season with salt, nutmeg and white pepper.

Use at once, or press plastic wrap onto the surface so no skin forms and keep in the fridge for up to 3 days. Whisk in a splash of milk to loosen it when reheating.