Makes one 9-inch tart
For the crust:
1 ½ cups all purpose flour
½ teaspoon kosher salt
10 tablespoons cold unsalted butter, cut into 1-inch pieces
1/3 cup ice-cold water
For the tart:
1 delicata squash, peeled, halved lengthwise and seeded
10 small shallots, peeled and trimmed
2 tablespoons extra-virgin olive oil
Kosher salt and freshly ground black pepper
1 cup crème fraiche
1 cup heavy cream
3 large eggs
1 teaspoon kosher salt
2 teaspoons minced fresh thyme
1 teaspoon minced fresh rosemary
½ teaspoon freshly ground black pepper
¼ pound blue cheese (I like Point Reyes' Bay Blue), crumbled
Preheat the oven to 375 degrees.
Make the crust: In the bowl of a food processor (or in a large bowl) pulse the flour and salt to combine. Scatter the cubed butter over the flour and pulse until the butter is in pea-size pieces. Drizzle in half of the cold water and pulse a few times. Add the remaining water and pulse a few more times, just until the dough begins to come together into a ball. Turn the dough out onto a sheet of plastic wrap. It may still be a bit crumbly, and this is OK; use the plastic wrap to help gather the dough into a ball, then tightly wrap and flatten into a disk. Refrigerate until cold, at least 30 minutes or up to overnight (the dough can also be well wrapped and frozen for up to 3 months).
Cut one half of the squash crosswise into half-moons about ½-inch thick. Cube the remaining squash half into ¾-inch cubes. Transfer to a bowl and drizzle with 1 tablespoon of the oil and season with salt and pepper. Arrange the squash slices and cubes in a single layer on one half of a rimmed baking sheet. Put the shallots in the (now-empty) bowl, drizzle with the remaining oil, season with salt and pepper and toss to coat. Transfer to the other half of the baking sheet, arranging them in a single layer. Transfer the pan to the oven and bake until the squash is soft and golden brown, turning once, about 20 minutes. Remove the pan from the oven and transfer the squash to a plate, taking care to leave the half-moons intact. Return the shallots to the oven and continue roasting until very soft, about 10 more minutes. Remove from the oven and let cool. When the shallots are cool, halve them and add to the plate with the squash.
Remove the crust from the fridge. On a lightly floured work surface with a lightly floured rolling pin, roll the crust into a 12-inch circle. Carefully transfer to a high-sided 9-inch tart pan with a removable bottom. Transfer to the refrigerator and chill until cold, about 30 minutes. Line the chilled shell with parchment paper and fill with pie weights. Place on a rimmed baking sheet, transfer to the oven and bake for 20 minutes. Carefully remove the pie weights and parchment and continue baking for 10 more minutes, until the crust is golden brown.
While the crust bakes, make the filling. In a large bowl whisk together the crème fraiche, heavy cream, eggs, salt, thyme, rosemary, and black pepper.
Let the parbaked crust cool slightly, then line with the roasted squash cubes and shallots. Pour the custard over, then scatter the blue cheese over the top. Arrange the half-moons of squash in a decorative design over the top of the tart. Transfer the tart (still on the rimmed baking sheet) to the oven and bake for 10 minutes. Reduce the oven temperature to 325 and continue baking until the custard is set, and the top is brown, about 30 minutes longer. Let cool until just warm, then cut into wedges and serve.