• 5-6 Large potatoes
• 150ml/1/4 pint milk
• 300ml/1/2 pint double cream
• 1 tbsp cornflour
• 100g/1/4lb Gruyere or Emmenthal cheese, grated
• salt
• freshly ground black pepper
• freshly grated nutmeg
• cayenne pepper
• 2 tbsp softened butter for greasing
• 2tbsp diced butter

1. Peel the potatoes and cut them into thin slices, then soak in cold water for 10 minutes. drain and pat dry

2. Prepare a cheese sauce. Heat the milk and double cream, then pour onto a paste made with 2 tbsp water and the cornflour. Stir in the grated cheese and simmer over a moderate heat, stirring constantly, until the cheese has melted and the sauce thickened. Season with salt, black pepper, nutmeg and cayenne pepper, then remove from heat.

3. Heat oven to 200C/400F/Gas 6.

4. Butter a medium-sized gratin dish generously. Cover the base with a layer of overlapping potatoes and season with salt, freshly ground black pepper and nutmeg.

5. Spoon one-third of the cheese sauce over the potatoes. Cover with another layer of overlapping potatoes and seson again with salt, pepper and nutmeg. Cover with half the remaining cheese sauce, and top with a third layer of overlapping potatoes. Season again and spoon over the rest of the cheese sauce. Dot with diced butter and bake for 15 minutes.

6. Reduce the oven heat to 190C/375F/Gas 5. Cover the potatoes with foil and continue to cook for 35 minutes. Remove from the oven.

7. Just before your guests sit down to lunch, remove the foil and return the dish to the oven for 20 minutes until crisp and golden on top.