1-Preheat the oven: Preheat your oven to 400°F.

2-Roll out the crust: On a lightly floured sheet of parchment paper, roll out the pie crust into a rough 12-inch circle.

3-Transfer to baking sheet: Slide the parchment paper with the crust onto a rimmed baking sheet.

4-Mix the filling: In a large bowl, whisk together lemon juice, vanilla, cornstarch, granulated sugar, brown sugar, and cinnamon until smooth.

5-Toss peaches with filling: Add sliced peaches and toss gently until coated; let sit for a minute or two to release juices.

6-Arrange peaches on crust: Spoon the peach filling onto the center of the crust and spread into an even circle, leaving a 2-inch border.

7-Fold the crust: Gently fold the outer edge of the crust up and over the peaches, pleating or crimping as you go, leaving the center open.

8-Add butter and toppings: Dot the peaches with cold butter pieces, brush the folded crust with milk, and sprinkle coarse sugar over the entire top.

9-Bake the galette: Bake for 25 to 30 minutes until the crust is deep golden brown and the filling is bubbling.

10-Rest and serve: Let the galette rest on the baking sheet for 5 minutes before transferring to a cooling rack or serving plate.