Gratin de Topinambours

• 1 kg/2¼ lb jerusalem artichokes
• 15 g/½

Peel the jerusalem artichokes and slice them very thinly. Cover with a cloth and set aside.

Prepare a béchamel sauce by melting the butter in a saucepan. Add the flour and stir continuously for 2 minutes over low heat to make a roux. Boil the milk and pour a little on to the roux, stirring with a whisk, then whisk in the rest of the milk and cook gently for 10 minutes.

Sieve the