Gratin savoyard

Peel the potatoes and soak them in cold water to stop browning.

Slice the potatoes on a mandoline, opening the hand halfway through and slicing with minimum pressure, or use the safety guard.

Shred Gruyere, Comte or Tomme de Savoie.

Grease a cast iron dish with butter or oil, line with parchment and lay in overlapping potato slices.

Season the layer with salt, pepper, garlic powder and nutmeg, add heavy cream and cheese; repeat twice and top with parmigiano reggiano.

Variation: bring the cream to a boil and infuse it with herbs, garlic, nutmeg, salt and pepper first.

Cover with microwave-safe plastic wrap and foil and bake at 350F / 180C for an hour and a half.

Uncover, raise the oven to 450F and bake 20 minutes more.

Variation: build the same layers in a baking tray or hotel pan; it can be made ahead, chilled and cut into shapes.

Variation: cut potato coins from the slices and build them in a tart ring, using clarified butter instead of cream so nothing escapes; drizzle more clarified butter over when finished.