Active Time

　　50 minutes

　　Total Time

　　2 hours 40 minutes

　　There’s no need to reduce your cream or pre-cook the kale for this cheesy, creamy casserole. Leaving the potatoes unpeeled bumps up nutrients and cuts the prep time, too.

　　

Ingredients

6–8 servings

　　4 slices seeded rye bread

　　1 large bunch kale (preferably Tuscan; about 12 ounces), ribs removed, leaves torn into 3" pieces

　　6 ounces good-quality Gruyère, grated on the large holes of a food processor blade or box grater (about 2 cups)

　　2 ounces good-quality Parmesan, grated on the large holes of a food processor blade or box grater (about ½ cup)

　　2 pounds yellow-fleshed potatoes (such as Yukon Gold), unpeeled, cut crosswise into ⅛"-thick slices (see Cooks' Note), divided

　　1 teaspoon dried thyme, divided

　　Kosher salt, freshly ground pepper

　　2 ½ cups heavy cream

　　2 garlic cloves, finely grated or pressed

　　3 tablespoons extra-virgin olive oil, divided

　　

Special Equipment

A 13x9x2" or 3-quart baking dish

　　

Step 1

Arrange a rack in center of oven; preheat to 350ºF. Arrange bread slices on a rimmed baking sheet and bake, flipping once halfway through, until dry and lightly toasted, 15–20 minutes. Let cool. Transfer to a resealable plastic bag and break into irregular, 1/2"–1" pieces. Transfer to a medium bowl; set aside.

　　

Step 2

Meanwhile, wash and spin-dry kale, then layer between paper towels or a large clean kitchen towel and pat dry.

　　

Step 3

Mix Gruyère and Parmesan in a medium bowl. Shingle one-quarter of potatoes in 3 or 4 rows, slightly overlapping, in bottom of baking dish. Sprinkle with one-quarter of thyme, 1/4 tsp. salt, and 1/8 tsp. pepper. Top with 2 cups kale and one-quarter of cheese mixture. Repeat 2 more times. Shingle remaining potatoes over cheese; top with 1/4 tsp. salt, 1/8 tsp. pepper, and remaining thyme. Reserve remaining kale and cheese.

　　

Step 4

Stir cream, garlic, 1/4 tsp. salt, and 1/8 tsp. pepper in a liquid measuring cup. Pour evenly over potatoes.

　　

Step 5

Bake gratin 40 minutes. Cover with foil and continue to bake until cream is bubbling and thick and potatoes are tender when pierced with a paring knife, 35–45 minutes more.

　　

Step 6

Meanwhile, toss reserved croutons with 2 Tbsp. oil in a medium bowl. Toss remaining kale with remaining 1 Tbsp. oil. Top gratin with kale, remaining cheese, then croutons, allowing kale pieces to peek through. Bake gratin until croutons are golden brown and exposed kale edges are well-crisped, about 15 minutes more. Let cool at least 10 minutes before serving.

　　

Do Ahead

Step 7

Bread can be toasted 3 days ahead. Store in an airtight container at room temperature.Kale can be torn, washed, and patted dry 3 days ahead. Wrap in paper towels, place in a resealable plastic bag, and chill.

　　

Step 8

Gratin can be made 1 day ahead. Let cool, then wrap tightly in plastic and chill. Bring to room temperature, cover with foil, and warm in a 300ºF oven until heated through, 15–20 minutes. Uncover and continue to warm to re-crisp croutons and exposed kale edges, about 5 minutes.

　　Cooks' Note

　　Use a mandoline to quickly cut potatoes into uniform-sized slices. To reheat casserole, bring to room temperature, cover with foil, and warm in a 300ºF oven until heated through, 15–20 minutes. Uncover and continue to warm to re-crisp croutons and exposed kale edges, about 5 minutes.