To make the crust, put the butter in a food processor with the flour and salt. Pulse until butter is pea sized. Add ice water, 2 tablespoons at a time until it starts to form a dough.
Transfer to a floured surface and cut in half. Cut one half into four pieces and reserve the other for another use. Wrap the four pieces in plastic and chill in the fridge for about 30 minutes.
While the dough is chilling, make the filling. Put the peaches, raspberries, flour, sugar, and vanilla in a bowl and stir well. Let sit until dough is done chilling.
To make the galettes, remove the pie crust from the fridge. Roll each piece into a 6-8 inch circle. Spoon a quarter of the filling in the center and fold the edges up, leaving about a 2 inch open center. Repeat with remaining pieces.
Transfer to a parchment lined sheet pan and brush each with the beaten egg, then sprinkle with sugar.
Bake for 45 minutes until crust is browned and filling is bubbly.
Let cool before serving.
Notes
Storing leftovers: Leftovers can be covered and stored at room temperature for up to two days.Variations: You can use any kind of summer fruit for these — any berry will work, and you can use peaches, apricots, cherries, or any mixture.Pairs well with:Toasted Vanilla Cardamom Coffee Sugar, Chocolate Chai Cold Brew, Earl Grey Lavender Latte