This butternut squash quiche is full of cozy fall flavors: roasted winter squash, tender leeks, and earthy sage. Encased in a flaky gluten-free crust and held together with luscious savory custard and creamy goat cheese, this quiche makes a special vegetarian main dish for holiday gatherings or weekend brunch.
Have the pie crust made, shaped in the pan, and chilled. You can parbake it along with the vegetables on the lower rack of the oven if you like, or parbake it ahead of time.
Prepare the veggies
Position racks in the upper and lower thirds of the oven. Preheat to 400ºF.
Place the prepared squash cubes on a baking sheet and toss to coat with the olive oil, ¼ teaspoon salt, and a little pepper. Roast in the upper third of the oven until golden and tender, 30-45 minutes, tossing once or twice.
To prepare the leek, slice it in half lengthwise, then cut it into ¼-inch pieces crosswise. Place the sliced leek in a large bowl filled with cool water and swish once or twice to remove any sandy dirt hanging out between the slices. Melt the butter in a medium-sized skillet over medium-low heat. When it sizzles, lift the leeks from the bowl and add them to the pan. Season with a few pinches of salt and cook, stirring occasionally, until it's very tender but not brown, 10-15 minutes.
Lower the oven temperature to 350ºF.
Make the custard
Place the flour, ½ teaspoon salt, and pepper in a medium-sized bowl. Add one of the eggs and whisk until smooth. Whisk in the remaining eggs, then the milk and cream. Cover and chill until needed, up to 2 days.
Make the quiche
Place the crust on a rimmed baking sheet to make it easier to maneuver and to catch any drips.
Layer the roasted squash, cooked leeks, slivered sage, and goat cheese into the parbaked quiche crust.
Carefully pour in the custard mixture until the quiche is as full as possible without overflowing; you may have a little extra.
Carefully transfer the quiche to the oven and bake until the top is golden and puffed, and a knife inserted near the center reveals no liquid, 45-60 minutes. Rotate the quiche once or twice for even baking.
Let the quiche cool to warm or room temperature to make it easier to slice, at least 20 minutes and up to several hours. Use a sharp knife to cut the quiche into wedges and serve warm or at room temperature.
Storage
The baked quiche will keep at cool room temperature for up to 3 hours. Extra quiche can be wrapped and refrigerated for up to 4 days. To reheat, place in a 350º oven or toaster oven until heated through, 10-15 minutes.
To freeze quiche, place cooled slices in an airtight freezer-safe container and freeze for up to 3 months. To reheat, place slices in a 350º oven or toaster oven until heated through, 15-20 minutes or as needed.
Notes
Do-Ahead:Many components can be made ahead to ease day-of prep.
The quiche crust dough can be made up to several days ahead and refrigerated for 3 days or frozen for up to 3 months.
Unbaked quiche crust can be wrapped and refrigerated for up to 2 days, or frozen for up to 3 months.
Parbaked quiche crust can be wrapped and stored at room temperature for up to 1 day, refrigerated for up to 1 week, or frozen for up to 3 months.
The squash and leeks can be cooked and refrigerated for up to 3 days.
The custard can be refrigerated for up to 3 days. Be sure to whisk it very well before baking to re-incorporate the flour into the custard.
The quiche is best the day that it’s baked when the crust is crisp. But baked quiche can be made 1 day ahead, covered, and refrigerated until ready to serve. Slice up the cold quiche and reheat slices in a 350º oven until warm, 10-15 minutes.
To freeze quiche, place cooled slices in an airtight freezer-safe container and freeze for up to 3 months. To reheat, place slices in a 350º oven or toaster oven until heated through, 15-20 minutes or as needed.