Roll out pie crust. Using a 3 inch biscuit cutter, or glass cut out circles. You should get about 12 per crust (enough for 6 pies).
Lay out circles. Place about 1 Tbls of dulce de leche in the center of each circle. Top with apple filling. Cover with another circle of dough, and use a fork to crimp the edges shut.
Place on a greased or lined baking sheet.
Whisk together egg and water. Brush over the top of the pies.
Using a sharp knife, slice 2 slits in the top of the pies.