Butternut Squash and Leek Galette

Ingredients

• 1 sheet of store-bought puff pastry, thawed
• 2 cups cubed butternut squash
• 1 large leek, white and light green parts only, halved lengthwise and thinly sliced
• 2 tablespoons olive oil
• Salt and freshly ground black pepper
• 1/4 cup crumbled feta cheese
• 2 tablespoons chopped fresh parsley

Directions

1. In a food processor, give the flour, cornmeal, sugar, and salt a quick whirl to mix them. Drop in the butter and pulse until it is worked through in little pea-size bits. Pour in the oil and water, then run the machine only until the dough gathers itself together. Pat it into a disk, cover it with plastic wrap, and chill it for at least 1 hour and up to 1 day.
2. Set an oven rack in the middle position and bring the oven to 425°F. Cover a large rimmed baking sheet with parchment, then slick the parchment with 1/2 Tbs. of the oil.
3. Spread the squash across the prepared sheet in a single layer. Brush it with 1 Tbs. of the oil, scatter the thyme sprigs onto the pan, and season the squash with 1/2 tsp. kosher salt. Roast until the pieces are barely soft and caramelized here and there, 20 to 25 minutes.
4. While the squash roasts, warm the remaining 2 Tbs. oil in a large skillet over medium heat. Stir in the leeks and garlic along with the pepper flakes and a pinch of kosher salt. Cook, stirring now and then and turning the heat down if the pan gets too enthusiastic, until the leeks soften and pick up browned spots, 5 to 8 minutes. Set them aside to cool.
5. In a small bowl, combine the cheese and parsley with a few grinds of pepper and a pinch of kosher salt. Use your fingers to break it up and bring it together.
6. Roll the dough into a 12-inch circle between 2 sheets of lightly floured parchment. It will be delicate and thin, so gently transfer the parchment holding the dough to a large baking sheet; for the moment, don’t worry if the dough drapes past the edge. If it splits now or later while you fold, no drama, just press the torn spots back together and keep going.
7. Scatter half of the goat cheese mixture, about 1/2 cup, in the middle of the dough, keeping a 1-inch border clear. Add the leeks over that, arrange the squash on top, then finish with the remaining 1/2 cup goat cheese mixture and the thyme leaves, still keeping a 1-inch border. Lift the outside edge of the dough up over the filling, making pleats as you work around the circle. Paint the pastry edge with the egg wash. Chill the galette for at least 30 minutes and up to 8 hours.
8. For baking, put an oven rack in the middle position and heat the oven to 400°F. Bake until the pastry is nicely browned, 30 to 35 minutes. Let it rest briefly before you cut it. Sprinkle with flaky sea salt. Serve it warm or at room temperature, with balsamic glaze on the side.