Spaghetti Squash and Potato Gratin

We had this Thanksgiving weekend, as an alternative potato dish that incorporated some of the squash of the season (we are a family that had butternut squash and sweet potatoes on Thanksgiving day and did not have a huge amount left over, so we do like our squash).  The dish really tastes like potatoes!

1  spaghetti squash
2 cups half and half
4 tablespoons unsalted butter
2 cloves garlic, chopped
1 teaspoon fresh thyme leaves, chopped
1 cup grated Parmesan
Kosher salt and freshly ground black pepper
2-3 pounds potatoes

Roast the squash.

Meanwhile, combine the cream, butter, garlic, thyme, 1/2 cup of the Parmesan, 1 1/2 teaspoons salt and 1/4 teaspoon pepper in a large saucepan. Peel the potatoes, then slice them paper thin on a mandoline, placing them in the cream mixture as you slice. Bring the mixture to a simmer over medium-high heat, then remove from the heat.

When the squash is cool enough to handle, slice it in half, scoop out the seeds, then scrape out the flesh with a fork into a medium bowl. Discard the skin and seeds.

Layer the bottom of the prepared baking dish with 1/2 the potatoes. Top with 1/2 the squash, then the remaining potatoes, then the remaining squash. Pour all the liquid from the potato mixture into the baking dish, and press the vegetables down to submerge. Sprinkle the remaining 1/2 cup Parmesan on top. Put the baking dish on a rimmed baking sheet, and bake until golden brown and a knife slides easily into the potatoes, about 1 hour. Let cool for 15 minutes before serving.