Mornay

Béchamel with Gruyère and a yolk. The gratin sauce — it browns where other sauces only dry out.

500 ml — whole milk

25 g — butter

25 g — plain flour

60 g — Gruyère, grated

20 g — Parmesan, grated

1 pc — egg yolk

1 pinch — nutmeg, grated

Make a Béchamel and take it off the heat. Stir in both cheeses while it is hot but not boiling — boiled cheese goes stringy and weeps fat.

Whisk the yolk into a spoonful of the sauce first, then stir that back in. Straight into the pan, the yolk sets in threads.

Gratins, cauliflower cheese, eggs Florentine, croque-monsieur.