Prepare 1 recipe of my 'All-Butter Pie Crust'; see separate video recipe for more in-depth instructions. Place the cold butter and flour into a food processor, along with the salt. Pulse the ingredients together for about 2 minutes, until a grainy mixture forms. Add the water and continue to pulse until a dough ball forms, about 30 seconds. Wrap the dough tightly in plastic wrap, then refrigerator for at least 1 hour, or overnight.

Preheat the oven to 375F. Next, prepare the peach filling. Slice the peaches thinly, then place into a large mixing bowl. Add the lemon juice, vanilla, sugar, flour and spices. Gently toss the peaches in the mixture until they're well coated.

Once the crust dough is chilled, transfer it onto a lightly floured surface. Flour a rolling pin, then roll the dough out into a large circle, about 14-inch in diameter. Line a baking sheet or perforated pizza pan with parchment paper, then transfer the dough onto the paper. Transfer the peaches onto the dough, spread them in even layer, leaving about 3 inches of dough along the edges. Gently fold the dough over the fruit.

Whisk the egg in a small ramekin with a fork, then use a pastry brush to brush the egg wash onto the edges of the pie crust. Bake the galette in the preheated oven for 45 to 50 minutes, until the edges of the tart are golden brown. Allow the tart to cool for at least 30 minutes, then serve warm with vanilla ice cream.