1 kg (2.2 lbs) floury potatoes, such as King Edward or Maris Piper
500 ml (2 cups) heavy cream
100 ml (1/2 cup) whole milk
3 cloves garlic, peeled and smashed
2 tablespoons butter, plus extra for greasing
1/2 teaspoon ground nutmeg
1 teaspoon salt
1/2 teaspoon black pepper
2 sprigs fresh thyme
Instructions
Start by preheating your oven to 160 degrees Celsius (320 degrees Fahrenheit). In a small saucepan over medium heat, combine the heavy cream, milk, smashed garlic cloves, and thyme sprigs. Bring the mixture to a gentle simmer, then remove it from the heat and let it steep for at least 10 minutes. This allows the aromatics to flavor the cream deeply. Use a bit of butter to generously grease a large baking dish.
Peel the potatoes and slice them very thinly, about 3 millimeters thick. Using a mandoline slicer is the best way to ensure uniform thickness, which helps the potatoes cook evenly. Crucially, do not wash or soak the potato slices after cutting, as you need the surface starch to thicken the creamy sauce during the baking process.
Remove the garlic cloves and thyme sprigs from the infused cream and discard them. Stir the salt, black pepper, and ground nutmeg into the cream. Arrange a layer of potato slices in the bottom of the greased baking dish, slightly overlapping them. Pour a small amount of the cream mixture over the layer. Repeat this process until all the potatoes and cream are used, finishing with a final layer of cream on top.
Place the dish in the center of the oven and bake for about 1 hour to 1 hour and 15 minutes. You want the potatoes to be completely tender when pierced with a knife and the top to be a beautiful golden brown. If the top is browning too quickly, you can loosely cover the dish with foil for the remaining cook time. Once finished, let the dish rest for 10 to 15 minutes before serving to allow the sauce to set.
