Creamy Potato Au Gratin

Instructions

1. 1Preheat your oven to 375°F (190°C). Butter a 9×13-inch (23×33cm) baking dish generously.
2. 2Slice the potatoes as thin and uniform as possible — a mandoline makes this easy and ensures even cooking. Pat the slices dry with a clean towel.
3. 3Melt the butter in a medium saucepan over medium heat. Add the garlic and cook, stirring, for 1 minute until fragrant but not browned.
4. 4Pour in the heavy cream and milk. Add the thyme, salt, pepper, and nutmeg. Heat over medium, stirring occasionally, until the mixture just begins to steam and simmer — do not boil. Remove from heat.
5. 5Arrange one-third of the potato slices in an overlapping layer in the prepared dish. Pour one-third of the cream mixture over the top. Sprinkle with one-third of the Gruyère and a little Parmesan.
6. 6Repeat the layers two more times — potatoes, cream, Gruyère and Parmesan — finishing with the remaining cheese on top.
7. 7Cover the dish tightly with aluminum foil. Bake for 45 minutes, until the potatoes are just tender when pierced with a knife.
8. 8Remove the foil and bake for an additional 25–30 minutes, until the top is deeply golden, bubbling, and the edges are caramelized.
9. 9Let the gratin rest for 10–15 minutes before serving — this allows the cream to thicken and the layers to set so it slices cleanly.
10. 10Garnish with fresh chives and serve straight from the dish.