Baked Brie and Caramelized Vegetable Pie

Preparation

1. Step 1

   Heat oven to 425 degrees.

2. Step 2

   In a large cast-iron or nonstick skillet, heat 2 tablespoons oil over medium-high. Add the mushrooms, season with salt and pepper and cook, stirring occasionally, until lightly browned and tender, 8 to 10 minutes. Transfer mushrooms to a large bowl, drizzle with soy sauce and toss to coat.

3. Step 3

   While the mushrooms cook, prepare the squash: On a large, foil-lined rimmed baking sheet, toss the squash with 1 tablespoon olive oil and the honey; season generously with salt and pepper. Spread out evenly then roast just until tender, about 15 minutes.

4. Step 4

   Heat 2 tablespoons oil in the skillet over medium-high. Add the brussels sprouts, shallots, garlic and rosemary; season with salt and pepper. Cook, stirring frequently, until tender and lightly caramelized, about 8 minutes.

5. Step 5

   Transfer the cooked brussels sprouts and squash to the bowl with the mushrooms. Stir to combine and generously season to taste with salt and pepper.

6. Step 6

   Wipe out the skillet, then heat the remaining 1 tablespoon oil over medium. Add the onion and thyme, season with salt and pepper, and cook, stirring occasionally, until lightly caramelized, about 10 minutes. Stir in the brown sugar, vinegar and ¼ cup water. Reduce the heat to medium-low and cook, stirring occasionally, until jammy, 10 to 15 minutes. Set aside. (Let the onion jam and vegetable filling cool completely at room temperature — or refrigerate for about 30 minutes to speed things up — before assembling the pie. If preparing in advance, you can cover and refrigerate them overnight or up to 3 days.)

7. Step 7

   When ready to bake your pie, line a large rimmed baking sheet with parchment paper. Working on a lightly floured surface, with a lightly floured rolling pin, roll out one sheet of puff pastry into a 10-inch square, then, using a sharp paring knife, cut it into a 10-inch circle. (If you have a 10-inch plate, you can use that as a guide.) Transfer to the baking sheet. Roll out the remaining sheet of pastry into a 12-inch square, then cut it into a 12-inch circle. If desired, decorate the top by arranging the scraps on top, or carve a light pattern into the top of the puff pastry using the tip of a sharp paring knife. (Be careful not to cut all the way through.)

8. Step 8

   Add half the vegetable mixture to the 10-inch round and arrange in an even layer, leaving a 1-inch border. Center the cheese on top; spoon the onion mixture over the cheese. Pat the remaining vegetable mixture evenly and tightly around the cheese, ensuring that the 1-inch border is clear.

9. Step 9

   Brush the exposed edges of the bottom pastry with the beaten egg. Fold the remaining piece of pastry in half, set it over the filling and unfold, carefully pushing out any air between the filling and pastry. Press the edges to seal and trim if you’d like to perfect the shape. Brush all the exposed puff pastry lightly with the beaten egg.

10. Step 10

    Bake until the puff pastry is deeply golden, 40 to 45 minutes. Let cool for 30 minutes to 1 hour. (If you cut the pie early, the cheese will flow out like lava; be patient and it will be molten but less messy.) Transfer to a platter and serve.