Instructions:

Make the Crust:

In a large bowl, whisk together the flour, salt, and sugar.

Add the chilled butter pieces and use a pastry cutter or your fingers to cut the butter into the flour mixture until it resembles coarse crumbs.

Gradually add the ice water, one tablespoon at a time, mixing until the dough just comes together. Be careful not to overwork the dough.

Form the dough into a disk, wrap it in plastic wrap, and refrigerate for at least 1 hour.

Prepare the Filling:

In a large bowl, combine the sliced peaches, sugar, lemon juice, vanilla extract, cornstarch, and cinnamon (if using). Gently toss to coat the peaches evenly. Let the mixture sit for about 10-15 minutes.

Assemble the Galette:

Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.

On a lightly floured surface, roll out the chilled dough into a rough circle about 12 inches in diameter. Transfer the dough to the prepared baking sheet.

Arrange the peach mixture in the center of the dough, leaving a 2-inch border around the edges.

Fold the edges of the dough over the peaches, pleating it as you go, to create a rustic crust. Brush the edges of the dough with the beaten egg and sprinkle with turbinado sugar.

Bake the Galette:

Bake in the preheated oven for 35-40 minutes, or until the crust is golden brown and the filling is bubbling.

Remove from the oven and let the galette cool on the baking sheet for about 10 minutes. Transfer to a wire rack to cool completely.

Serve:

Serve the peach galette warm or at room temperature. It pairs wonderfully with a scoop of vanilla ice cream or a dollop of whipped cream.