In a large mixing bowl, whisk together flour and salt. Cut in cold butter until crumbled. Add ice water, mix until dough forms. Shape into a disk, wrap in plastic, chill for 30 minutes.

Slice peaches and combine with sugar, cornstarch, lemon juice, cinnamon, and vanilla in a bowl. Toss gently to coat.

Preheat oven to 400°F (200°C). Roll out the chilled dough on a floured surface to a 12-inch circle. Transfer to a parchment-lined baking sheet.

Spoon peach mixture into the center, leaving a 2-inch border. Fold edges over peaches, brush with egg, and sprinkle with coarse sugar.

Bake for 35-40 minutes until the crust is golden and peaches bubbly. Allow to cool for 15 minutes before serving.