Combine peaches, cherries, granulated sugar, corn starch, vanilla, lemon juice, and cinnamon in a bowl. Toss to mix well.
Roll out pie crust on a parchment-lined surface -- if using a homemade crust, roll out to a 14-inch circle. Brush crust with egg white.
Spoon filling onto inner part crust and fold edges of crust over filling. Brush exposed crust edges with egg yolk and sprinkle turbinado sugar over both crust and filling.
Bake at 375°F for 35-40 minutes, or until outside of crust is golden brown.
Allow to cool 5-10 minutes and serve warm with ice cream, if desired.
Video
Notes
*If you use frozen fruit, thaw it in a colander over a bowl to drain out liquid before adding to galette.**If you don't have turbinado sugar, granulated sugar will work fine.