Roll out a prepared pie crust between two layers of plastic wrap or lightly greased parchment paper. Place in the fridge to keep cold while preparing the filling and topping.
Peel the peaches and place in a bowl or use frozen peaches. Add the flour, sugar, salt, and ground ginger and stir to combine.
Bake the crostata on a sheet pan on parchment paper. Remove the plastic wrap from the pie crust and keep the crust on the parchment if you have rolled it out. Pile the filling in the center so that there is a two-inch rim all around the edge of the crust.
Fold the edges of the crust toward the center of the crostata. Egg wash the edges of the crust with a beaten egg or egg yolk.
Top the peach crostata with the spiced crumble and sprinkle regular sugar or turbinado sugar around the pie crust for extra crunch.
Bake at 350 degrees for 35-45 minutes or until the crust is golden brown. Baking time depends on if you use fresh or frozen peaches.