Step 1

Preheat an oven to 375°F (190°C).

Step 2

In a large sauté pan over medium heat, combine the kale and 1/4 cup (2 fl. oz./60 ml) water and cook, stirring occasionally, until the kale is wilted, about 4 minutes. Drain the kale, transfer to a bowl and set aside.

Step 3

In the same pan over medium heat, melt the butter. Add the shallot and cook, stirring occasionally, until translucent, 1 to 2 minutes. Add the flour and cook, stirring constantly, until fragrant, 1 to 2 minutes. Slowly stir in the stock and cream and cook until the sauce coats the back of a spoon, 1 to 2 minutes. Add the Gruyère and 1 Tbs. of the sage and stir until the cheese has melted, about 1 minute. Season with salt and pepper.

Step 4

In a 9-by-13-inch (23-by-33-cm) gratin dish, layer half each of the kale, squash and sauce, then repeat with the remaining kale, squash and sauce. Cover the dish with aluminum foil and bake until the squash is fork-tender, about 40 minutes.

Step 5

Meanwhile, in a small bowl, stir together the panko, Parmesan and the remaining 1 Tbs. sage.

Step 6

Uncover the pan and sprinkle the gratin evenly with the panko mixture. Bake until the top is golden brown and the gratin is bubbling at the edges, 10 to 15 minutes more. Let stand for 5 minutes before serving. Serves 6 to 8.

Step 7

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