Potato and Swiss Chard Gratin

Ingredients

• 2 tablespoons unsalted butter, plus more for greasing the baking dish
• 1 pound Swiss chard (about 2 bunches)
• 4 garlic cloves, finely chopped, divided
• Kosher salt
• Freshly ground black pepper
• 2 pounds russet potatoes (4-5 potatoes), scrubbed
• 2 ½ cups heavy cream, divided
• ¼ teaspoon ground cayenne
• ¼ teaspoon ground nutmeg
• 1 ½ cups coarsely grated Gruyère (about 6 ounces)
• 1 ½ cups finely grated Parmesan (about 6 ounces)
• Finely chopped chives or parsley, for serving

Instructions

1. Preheat oven & grease dish
1. Preheat the oven to 375F and arrange the rack in the center.
2. Butter a 3-quart gratin or 9x13” baking dish.
2. Prep Swiss chard
1. Separate the Swiss chard leaves from the stems, stack the leaves, and slice into ½-inch ribbons. Thinly slice stems into ¼-inch pieces.
2. Heat a large frying pan over medium. Melt 2 tablespoons. butter, then add half the garlic and cook, stirring, until fragrant, about 30 seconds. Add chard stems, season with salt and pepper, and cook until softened, about 2 minutes. Add the leaves and cook until wilted and most of the liquid has evaporated, 3–5 minutes.
3. Transfer to a bowl and let cool slightly.
3. Prep potato mixture
1. In a large bowl, combine 1 ½ cups cream, ½ cup Gruyère, ½ cup Parmesan, remaining garlic, cayenne, and nutmeg. Thinly slice the potatoes, about ⅛-inch thick, using a mandoline or sharp knife (no need to peel the potatoes). Chef’s Tip: Quickly add the slices to the cream mixture to prevent oxidation (or keep submerged in cold water until ready to use).
2. Season with ½ teaspoon Diamond Crystal or ¼ teaspoon Morton kosher salt and freshly ground black pepper to taste; mix well to coat.
4. Assemble gratin
1. Shingle slightly overlapping slices of potato into the prepared dish to form a solid layer, tucking smaller pieces into gaps, and continue until you’ve used about half. Top with the cream mixture and another ½ cup each Gruyère and Parmesan.
2. Spread the cooked chard evenly over the potatoes, leaving behind any excess cooking liquid in the bowl.
3. Layer the remaining potatoes on top, pour the remaining 1 cup cream over, and sprinkle with the rest of the Gruyère and Parmesan.
5. Bake & serve
1. Cover with foil and bake until potatoes are very tender, 60–90 minutes.
2. Remove the foil and bake until the top is golden brown, another 30 minutes more.
3. Let rest 10 minutes before serving. Garnish with chives or parsley.