For pastry:

1. Combine the flour, sugar and salt in a food processor and pulse once. Remove the butter from the refrigerator just before using and slice the one stick of butter into small cubes. Pulse the food processor until the mixture is the size of small peas (about 15 times). Then while the food processor is running, very slowly pour the ice water through the spout until the dough forms a ball. Remove the dough from the food processor and wrap in wax paper and place in the refrigerator for at least 1 hour.

For the filling:

1. Cut the the butter into small cubes and add to a medium bowl. Add the flour, sugar and salt to the bowl and combine all the ingredients. Slice each peach into eighths. Add the peach slices to the flour-butter mixture and toss. Add the lemon juice and stir until all the ingredients are combined, with no lemon juice at the bottom of the bowl.

For the crostata:

1. Preheat oven to 450 degrees.
2. Remove the dough from the refrigerator and place on a floured surface. Add flour to the surface of the dough. Flatten the dough out into a round disk. Roll out into a large circle with a rolling pin. If the dough sticks to the rolling pin or the rolling surface, add more flour. Transfer the rolled out dough to the baking sheet.
3. Spoon the peach mixture into the center of the dough. Fold up the dough around the filling in a pleat pattern. Press lightly to seal. Make an egg wash by lightly whisking together the egg white and 1 tablespoon of cold water. Brush the egg wash on the crostata’s dough with the pastry brush.
4. Bake for about 20 minutes or until the crust is golden brown. Check after about 10 minutes of baking. If the crostata is browning too fast, place a piece of aluminum foil over the crostata. Cool the crostata to room temperature, then slice and serve.