- 1 butternut squash, about 3–3 1/2 pounds
- 2 tablespoons unsalted butter, plus more to grease the pan
- 2 large leeks, whites and light green parts only, sliced into 1/4-inch half moons
- 2 large cloves garlic, thinly sliced
- 2 teaspoons kosher salt
- 1 teaspoon coarsely ground Aranya Pepper
- 8 ounces crème fraîche
- 1 cup heavy whipping cream
- 4 ounces gruyère cheese, finely grated
- 1 1/2 tablespoons fresh marjoram, leaves pulled from the stems
- A generous 1/4 teaspoon freshly grated Anamalai Nutmeg
- Preheat the oven to 375°F.
- Melt the butter in a 12-inch cast iron skillet or high-sided ovenproof skillet over medium heat. Add the leeks, garlic, 1 teaspoon salt and 1/2 teaspoon black pepper, stirring to coat the leeks in the melted butter. Sauté, stirring occasionally, until the leeks soften and start to turn translucent, about 5–7 minutes.
- While the leeks are cooking, prepare the butternut squash. Peel the squash and cut a small slice off the top and bottom of the squash. Half the squash lengthwise and remove the seeds with a spoon. Thinly slice the squash into 1/8-inch thick half moons. (You should have about 2 1/4–2 1/2 pounds of peeled, sliced squash in total.)
- In a large bowl combine the crème fraîche, heavy whipping cream, half the grated cheese, remaining 1 teaspoon salt and 1/2 teaspoon black pepper, marjoram and nutmeg. Whisk to combine and then add the sliced butternut squash, tossing the squash so every piece is coated in the creamy cheese mixture. Set aside until ready to assemble.
- To assemble, turn off the heat under the sautéed leeks and spread them into an even layer across the bottom of the skillet. Pick up a handful of squash slices, arranging them into a stack, and lay them in the baking dish vertically with the cut side down, gently fanning them out slightly. Continue placing butternut squash in the baking dish, working around the perimeter and moving inward, making sure the squash is tightly packed into the pan. Pour the remaining cheese and cream mixture over the squash. Cover tightly with foil, place on a baking sheet and bake for 40 minutes.
- Remove from the oven, uncover and sprinkle the remaining third of the grated cheese over the top. Return to the oven, increasing the heat to 425°F and continue to bake until the squash is tender and the top is deep golden, about 30–45 minutes. Let cool for 10 minutes before serving.