1. Assemble the solar cooker.
2. Mix in the egg and water or milk to make the egg wash.
3. Roll out the store bought pie dough and lay it over the metal 9 inch cake pan.
4. Pour in the apple pie filling in the center and fold in the dough from the sides.
5. Brush the egg wash on the sides.
6. Sprinkle in the granulated sugar on the top.
7. Place the cake pan within the larger glass bowl of the solar cooker and let it sit on the reflector in the sun for 2 and a half hours.