Preparation

• Preheat the oven to 400°F with a rack in the center position.
• Arrange the squash in a single layer in an 8 x 8-inch or 7 x 10-inch baking dish. Toss with 1 tablespoon of the olive oil and 1 teaspoon of the salt until coated. Bake for 25 minutes.
• Meanwhile, heat the butter and remaining 1 tablespoon oil in a large skillet over medium heat. Once the butter has melted, add the shallots and cook, stirring occasionally, until tender, about 4 minutes. Stir in the garlic, sage, and thyme and cook, stirring, until fragrant, about 1 minute. Add the heavy cream, nutmeg, and remaining ½ teaspoon salt and cook, stirring, until combined and steaming, about 5 minutes. Add the Gruyère and Parmesan, then reduce the heat to low. Cook, stirring, until the cheese has melted, about 5 minutes.
• Once the squash has roasted for 25 minutes, remove from the oven, leaving the oven on. Pour the cheese sauce over the squash, then return to the oven. Bake until the sauce has thickened and the squash is tender, about 20 minutes more.
• Let cool for 5 minutes, then top with the pepper and sage before serving.