01 - Preheat the oven to 425°F. Line a baking sheet with parchment paper.
02 - Combine butternut squash cubes, apple slices, and red onion in a large bowl. Toss with olive oil, thyme, salt, and pepper. Spread the mixture evenly on the prepared baking sheet.
03 - Roast for 20 to 25 minutes, stirring once halfway through, until the squash is tender and lightly caramelized. Remove from oven and let cool slightly.
04 - In a food processor or large bowl, combine flour and salt. Add cold, cubed butter and pulse or cut in with a pastry blender until mixture resembles coarse crumbs. Gradually add ice water, mixing just until dough forms. Shape into a disk, wrap in plastic wrap, and refrigerate for 20 minutes.
05 - On a lightly floured surface, roll dough into a 12-inch circle. Transfer to a parchment-lined baking sheet.
06 - Arrange roasted squash, apples, and onions over the center of the dough, leaving a 2-inch border. Drizzle with honey or maple syrup and sprinkle with crumbled cheese, if using.
07 - Fold the dough edges over the filling, pleating as needed. Brush crust with beaten egg and sprinkle with coarse sugar, if desired.
08 - Bake for 25 to 30 minutes, or until crust is golden brown and crisp. Allow to cool slightly before slicing and serving.