01 - In a large bowl, whisk together flour and salt. Add cold butter and cut in with a pastry cutter or fingers until mixture resembles coarse crumbs. Drizzle in ice water and mix just until dough comes together. Shape into a disk, wrap in plastic, and refrigerate for at least 30 minutes.
02 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
03 - Heat olive oil in a large skillet over medium heat. Add zucchini, yellow squash, asparagus, sugar snap peas, and red onion. Sauté for 5–6 minutes until just tender. Add garlic, salt, pepper, and thyme; cook 1 minute more. Remove from heat and cool slightly.
04 - Roll out chilled pastry on a lightly floured surface into a 12-inch circle. Transfer to prepared baking sheet.
05 - Spread half the goat cheese over the center of the pastry, leaving a 2-inch border. Arrange sautéed vegetables over the cheese. Top with remaining goat cheese.
06 - Fold pastry edges up and over the filling, pleating as needed. Brush pastry with beaten egg.
07 - Bake 35–40 minutes, until crust is golden and crisp. Let cool 10 minutes before slicing.