In a large bowl, stir together all ingredients. Let stand until ready to assemble.
Place the fruit filling in the middle of the dough and fold over the edges. Brush the beaten egg white on the crust (optional.)
Place the Galette on a baking stone or a baking sheet lined with parchment paper. Bake on 425F for 30-35 min. Let cool a bit before serving. Serve with vanilla ice cream!
Total time does not include one hour of time to refrigerate pastry dough to make it easier to to handle.
Brushing the pastry dough with egg wash (beaten egg white) makes the dough brown and shiny when it comes out of the oven. This step is optional.