Root Vegetable Gratin

Ingredients

• ●2 pounds mixed root vegetables (any combination of potatoes, sweet potatoes, parsnips, celery root, turnips), peeled and sliced ⅛ inch thick (a mandoline is your friend)
• ●1½ cups heavy cream
• ●1 cup whole milk
• ●3 cloves garlic, minced
• ●2 teaspoons fresh thyme leaves
• ●1 teaspoon salt
• ●½ teaspoon freshly ground black pepper
• ●¼ teaspoon ground nutmeg
• ●1½ cups Gruyère cheese, grated (about 6 ounces)
• ●½ cup Parmesan cheese, grated
• ●2 tablespoons butter, for the dish

Method

1. Preheat your oven to 190°C (375°F). Butter a 9x13-inch baking dish generously.
2. In a saucepan, combine the cream, milk, garlic, thyme, salt, pepper, and nutmeg. Heat over medium until it just begins to simmer. Remove from heat.
3. Combine the Gruyère and Parmesan in a bowl.
4. Layer one-third of the sliced vegetables in the prepared dish, overlapping slightly. Pour one-third of the cream mixture over. Sprinkle with one-third of the cheese. Repeat twice more, finishing with cheese on top.
5. Press the layers down gently with your hands or a spatula so the cream rises up around the vegetables.
6. Cover tightly with foil. Bake for 45 minutes.
7. Remove the foil and bake for 25 to 30 minutes more, until the top is deeply golden and bubbly and a knife slides through the vegetables with no resistance.
8. Let rest for 15 minutes before serving. The gratin will set up slightly as it cools, making it easier to serve.
9. *Storage:** Refrigerate for up to 4 days. Reheat, covered, in a 177°C (350°F) oven for 25 minutes.
10. *Seasonal note:** A mandoline (or the slicing blade on a food processor) makes this recipe dramatically easier. Uniform thickness matters — if some slices are thick and others thin, they cook unevenly. The mix of root vegetables gives the gratin layers of different flavors and textures. Sweet potato adds sweetness, parsnip adds nuttiness, celery root adds an herbal depth. All of them get silky in the cream.