Preheat oven to 400F/200C. Prepare a baking sheet/tray with either a silicone baking mat or parchment paper.
Roll out the dough on a floured surface until about as thin as you are comfortable with (around ⅛in/2-3mm) and cut out circles - I used my largest scone/pastry cutter which is about 2 ¾in diameter.
Put a heaped spoonful of the pumpkin mixture slightly to one side of each pastry circle, but away from the edges. They should look as if they'll be fairly full but with enough space to fold one side over then seal the edges.
Carefully pull together the sides of the pastry and press the two edges together. This is easiest by folding over the side without the filling then pressing down the edge, taking care not to press out the filling or have an air bubble. Press together with the tip of a fork to seal. Alternatively, crimp the edges by folding over the edge, in towards the filling, and pressing with your thumb, then folding in the next edge again and again to form the braid-like edge.
Place the formed empanadas on top of the prepared baking sheet, with a little space between them. Gently prick the top of each to allow steam to escape. Brush the pastry with the reserved egg white (and add coarse sugar, if you like).
Bake for approx 20 minutes until the empanadas are starting to brown.