Ingredients

• 1.5 kg (approx. 3.3 lbs) Maris Piper or Desiree potatoes, peeled
• 2 cloves garlic, crushed
• 600ml (approx. 2½ cups) double cream (heavy cream)
• 300ml (approx. 1¼ cups) full-fat milk
• 1 tsp salt
• ½ tsp freshly ground black pepper
• A pinch of freshly grated nutmeg
• 50g (approx. ½ cup) Gruyère cheese, grated (optional)
• A knob of butter, for greasing

Step-by-Step Instructions

1. Preheat your oven to 180°C (160°C fan/350°F/Gas Mark 4). Lightly butter a large ovenproof gratin dish (approximately 25x30cm or 10x12 inches).
2. Thinly slice the peeled potatoes, about 2-3mm thick. A mandoline makes this wonderfully easy, but a sharp knife will do beautifully. There's no need to rinse them, as the starch helps to thicken the sauce.
3. In a large saucepan, combine the double cream, milk, crushed garlic, salt, pepper, and nutmeg. Bring the mixture gently to a simmer over a medium heat, stirring occasionally.
4. Add the sliced potatoes to the simmering cream mixture. Cook for about 5-7 minutes, stirring gently, until the potatoes have softened slightly but are still firm. This step ensures they cook through evenly in the oven.
5. Carefully spoon the potato mixture into your prepared gratin dish, spreading them out evenly. Pour over any remaining creamy liquid from the pan.
6. If using, sprinkle the grated Gruyère cheese evenly over the top.
7. Bake in the preheated oven for 50-60 minutes, or until the potatoes are tender when pierced with a knife and the top is beautifully golden brown and bubbling.
8. Allow to stand for 5-10 minutes before serving. This allows the sauce to settle and thicken slightly, ensuring sheer perfection.