Potato and Swiss Chard Gratin

Preparation

1. Step 1

   Heat the oven to 350 degrees, and place rack in the center. Bring a large pot of lightly salted water to a boil; set a bowl of ice water on the side. Boil the chard leaves until tender, 3 to 5 minutes, then transfer with a slotted spoon to the ice water. Squeeze them dry and chop roughly. Boil the diced stems until tender, 3 to 5 minutes. Drain well and add to chopped chard leaves.

2. Step 2

   In a small saucepan, bring the heavy cream, garlic, shallot, thyme and bay leaf to a simmer. Cook until reduced by half, about 25 minutes. Strain out the solids and add the nutmeg.

3. Step 3

   Meanwhile, slice the potatoes into ⅛-inch-thick rounds with a mandoline or sharp knife. Butter a 12- to 14-inch gratin dish. Assemble the gratin by layering the ingredients in this order: a single, slightly overlapping layer of one-third of the potato slices, a sprinkling of salt and pepper, one-third of the Gruyère, half the Swiss chard and one-third of the reduced cream. Repeat once, and then top with one more layer of potato, salt and pepper, and the rest of the Gruyère and cream.

4. Step 4

   Bake until the top is browned and the potatoes are fork-tender, about 45 minutes.