Ingredients

• 3 pounds assorted root vegetables, peeled (see Tip) and cut into 1/8-inch-thick slices
• 3 tablespoon extra-virgin olive oil, divided
• 1 cup thinly sliced shallots
• 1 1/3 cups low-fat milk, divided
• 3 tablespoon all-purpose flour
• 1 1/2 cups finely shredded Gruyère cheese, divided
• 1 tablespoon chopped fresh thyme, or 1 teaspoon dried
• 1/2 teaspoon salt
• 1/4 teaspoon freshly ground pepper
• 1 cup fresh whole-wheat breadcrumbs, (see Tip)

---

Cooking Directions

Step 1

Preheat oven to 400°F. Coat a 9-by-13-inch baking dish with cooking spray.

Step 2

If using parsnips, quarter lengthwise and remove the woody core before cutting into 1/8-inch thick slices. Cook vegetables in a large pot of boiling water until barely tender, about 5 minutes. Drain.

Step 3

Heat 2 tablespoons oil in a medium saucepan over medium heat. Add shallots and cook, stirring occasionally, until light brown, 3 to 4 minutes. Add 1 cup milk and bring to a simmer. Combine flour and the remaining 1/3 cup milk in a small bowl to make a smooth paste; stir into the hot milk and cook, whisking constantly, until the sauce bubbles and thickens, 1 to 2 minutes. Remove from the heat. Stir in 3/4 cup cheese, thyme, salt and pepper.

Step 4

Combine breadcrumbs, the remaining 3/4 cup cheese and 1 tablespoon oil in a bowl.

Step 5

Layer the vegetable slices in the prepared baking dish. Pour the cheese sauce over the top and top with the breadcrumb mixture.

Step 6

Bake the gratin until it is bubbling and the top is golden, 30 to 40 minutes. Let cool for 10 minutes before serving.