This soul-warming dish is French comfort food with some twists that are family friendly, fresh, and filling. Gluten free, lower in carbs, and mild in flavor, the gratin has a hint of smoke from the cheese that highlights the subtle nuttiness of the sunchokes and celery root. It’s a creamy-cheesy dish, full of hidden fiber and plenty of super-rich deliciousness. Get out the slicing blade of your food processor or a mandoline (with a guard) to make the thin slices that insure quick cooking.
- Nonstick vegetable oil spray
- 6 leeks
- 6 tablespoons salted cultured butter (any European butter)
- 2 tablespoons rice flour or potato starch
- ½ teaspoon freshly ground white pepper
- 1 teaspoon celery salt
- 2 cups nonfat milk, plus ½ cup more if needed, at room temperature
- 1 cup freshly shredded Parmesan cheese, divided
- ¼ teaspoon freshly grated nutmeg
- 1 pound sunchokes (Jerusalem artichokes), peeled and sliced into ⅛- to ¼-inch thick pieces and acidulated (see Kitchen Tip)
- 1 celery root (celeriac), peeled and sliced in ⅛-inch thick pieces and acidulated (see Kitchen Tip)
- 2 cups shredded smoked Gouda or smoked mozzarella cheese
- 3 large Granny Smith or tart green apples, peeled and sliced ½-inch thick and acidulated (see Kitchen Tip)
- Preheat the oven to 375°F. Spray a 2-quart casserole or baking dish with nonstick vegetable oil spray and set aside.
- Clean leeks.
- To make the sauce, in a medium saucepan, heat the butter over high heat. As soon as it begins to foam, lower the heat to medium and add the flour, whisking constantly, until it is thoroughly incorporated and takes on the consistency of a paste. Immediately add the 2 cups milk and whisk very well. When the mixture is fully heated through and just starting to bubble at the edges, add the pepper, celery salt, ½ cup of the Parmesan cheese, and nutmeg. Remove from the heat.
- To assemble the gratin, arrange a layer of the artichokes in the prepared dish, placing them all over the bottom in a single layer. Top with a layer of celery root. Spoon half of the sauce over the gratin and spread lightly with the back of a wooden spoon to coat the surface. (If the sauce is too thick, add a little more milk and stir to incorporate before you add it to the gratin.) Layer ½ cup of the Gouda or mozzarella cheese on top. Drain the leeks and layer the leeks and apples on top of the cheese and spread the rest of the sauce on top. Top with the remaining Parmesan and Gouda or mozzarella cheese, spreading the cheeses evenly over the surface.
- Bake for 45 to 50 minutes, or until the top is crusty and chestnut brown, the cheese is melted throughout and the vegetables are soft and cooked through. Serve immediately. The gratin can be covered, refrigerated and reheated.
The sunchoke, celery root, and apples should be cut before you start the sauce. The easiest way to keep them from browning for the few minutes it takes to make the sauce is to acidulate them—let them sit in a big mixing bowl filled with water to cover and the juice of 1 lemon. Acidulation works for other vegetables that brown quickly, such as regular artichokes and potatoes, but it will soak up a bit of lemon flavor. In this dish, it works very well; in some potato dishes, it won’t always. For sweet dishes that require acidulation, such as apples or bananas, you can use a little orange juice, white grape juice, or apple juice.