01 - In a large bowl, combine the flour and salt. Add cold butter and cut in with a pastry blender or fingers until the mixture resembles coarse crumbs. Gradually add ice water, mixing just until the dough forms. Shape into a disk, wrap in plastic, and refrigerate for at least 30 minutes.
02 - Preheat the oven to 400°F (200°C).
03 - Arrange zucchini, bell pepper, red onion, and cherry tomatoes on a baking sheet. Drizzle with olive oil, season with salt and pepper, and toss to coat evenly. Roast for 15 to 18 minutes until tender but not mushy. Remove and allow to cool slightly.
04 - On a lightly floured surface, roll out the chilled dough into a 12-inch circle about 1/8 inch thick. Transfer it to a parchment-lined baking sheet.
05 - Arrange the roasted vegetables in the center of the dough, leaving a 2-inch border around the edges. Sprinkle goat cheese and thyme evenly over the vegetables.
06 - Fold the edges of the dough over the filling, pleating as necessary to create a rustic border, leaving the center exposed.
07 - Brush the dough edges with the beaten egg to promote a golden crust during baking.
08 - Bake for 30 to 35 minutes until the crust turns golden brown. Allow to cool slightly before slicing and serving.