Make the filling: in a saucepan over medium heat, combine sugar, cornstarch, and water and whisk constantly as it comes to a simmer. Let simmer for 2-3 minutes, or until thickened.

Remove from the heat and stir in the lemon juice and peaches. Transfer to a shallow bowl and place in the refrigerator to let cool completely and thicken.

When the filling has cooled, roll out both pie crusts and cut twenty 3 ½ inch (9cm) circles. Place 10 circles on the prepared baking sheet.

Mound a small amount of filling onto the center of each circle on the baking sheet, brush the edges with the egg wash and place the remaining 10 pie crusts on top, pressing with your fingers or a fork to seal the edges.

With a thin knife, cut slits in the top crust for venting and brush all over with the remaining egg wash. Sprinkle the crust with the coarse sugar.

Bake for 30-35 minutes, or until the crust is golden brown. Serve warm or at room temperature.

Store these pies loosely covered at room temperature for up to 2 days. Refresh in the oven at 300°F (150°C) for 10 minutes.