Heat your oven to 375°F (190°C). Line a large baking pan with parchment paper. Carefully cut the pumpkin into halves and scoop out the seeds with a spoon. Place the pumpkin halves face down in the parchment lined pan.  Peel the apples, cut them in half, scoop out the center core, and fill with equal amounts of butter. Place the apples with the filled core side up next to the pumpkins. Place the pan in the heated oven, and roast for 1 hour.

Meanwhile, prepare the crust. In the bowl of a food processor, combine the flour along with the baking powder, salt, and sugar. Pulse once or twice to combine well. Cut the butter into slices, add to the bowl, pulsing until the mixture makes a course meal. Add the eggs one at a time, pulsing to combine well. Turn the food processor on and add the water through the feed hole. Once the dough gathers into a ball, turn off the food processor. Remove the dough and knead by hand on a floured surface until it is no longer sticky. Divide the dough into 18 equal size balls. Knead each piece lightly to coat with flour. Shape each equally sized piece into a flat patty. Place the pieces in a bowl, and store in the refrigerator for at least one hour.

Once they are roasted, remove the pumpkin and apples from the oven, and allow to cool completely. Using a large spoon, scoop the pumpkin flesh out of the pumpkin skin. You will only need 1 lb. (500g) of the pumpkin flesh. If you have leftover, freeze it for later use. Chop the apples into a ½” (1cm) dice. Place the pumpkin and apples in a large bowl and add the cinnamon. Stir to combine well. This should be a chunky mixture, but not too chunky.

To make the empanadas, roll each of the chilled dough patties into circles on a floured surface. Roll the circles to approximately 8” (20cm) in diameter. Add a large spoonful of the filling to the center of the circle. Fold the dough over the top to make a half-moon shape and seal the edges with a fork. Crimp the edges decoratively, if desired.

If you turned off the oven after roasting the pumpkins, turn it back on to preheat to 375°F (190°C) while you continue to shape all of the empanadas. Place the formed empanadas on a baking sheet lined with parchment paper. Bake the empanadas for 25-30 minutes until they are golden brown. Remove to a cooling rack and allow to cool completely before serving. Place the empanadas on a serving place, and top with a walnut half. Drizzle over the dulce de leche. If desired, serve more dulce de leche on the side for dunking.