One 1 ½ pound butternut squash
¼ cup extra-virgin olive oil
Kosher salt and freshly ground pepper
2 tablespoons unsalted butter
1 large shallot
1 pound assorted mushrooms, trimmed and cut
1 teaspoon sherry vinegar
Large pinch of dried nutmeg
All-purpose flour, for dusting
14 ounces chilled all-butter puff pastry
2 large egg yolks
¼ cup creme fraiche
¼ pound Gruyere cheese
2 teaspoons chopped thyme

STEP 1: The Squash

Preheat the oven to 375°
Peel, seed and cut the Squash into ½ inch pieces.
Toss cut squash in a bowl with 2 tablespoons of the oil.
Spread the squash on a baking sheet, season with salt & pepper.
Bake for 25 minutes, until just tender, transfer to a bowl.
Increase the temperature to 400°.

STEP 2: Mushrooms & Shallots

Meanwhile, in a skillet, melt the butter in the remaining 2 tablespoons oil.
Thinly slice the shallot, add the shallot and cook over moderate heat, stirring, until softened.
Trim and cut mushrooms into 1 inch pieces, add to shallots, cover and cook, stirring until tender, approximately 7 minutes.
Season with salt and pepper and remove from the heat. Toss with the vinegar and nutmeg and add to squash.

STEP 3: The Pastry

Line a baking sheet with parchment paper.
On a floured work surface, roll the puff pastry out to 12 ½ by 14 ½ inches. Using a knife trim the pastry to 12 by 14 inches.
Transfer to the baking sheet and prick the pastry with a fork all over except for a ½ inch border.
Bake the pastry for 20 minutes, until golden; pierce with a fork if it puffs during baking. Let cool.

STEP 4: Cheese & Herbs

Grate the Gruyere.
Chop the thyme.
Stir the egg yolks, creme fra’iche, Gruyere, thyme, 1/2 teaspoon of salt and 1/4 teaspoon of pepper into the mushrooms and squash. Spread the mixture on the pastry inside the border.
Bake for 15 minutes, until the cheese is melted.