Prepare the dough: In a large bowl, mix the flour, sugar, and salt. Add the cold vegan butter cubes and use a pastry cutter or fork to incorporate the butter until the mixture resembles small pea-sized pieces.
Incorporate the water: Pour in the ice water and mix until the dough forms a shaggy texture.
Form the dough: Transfer the dough onto a silicone mat or your work surface. Press and fold the dough over itself 2-3 times to create layers of butter. Don’t knead it.
Chill the dough: Divide the dough into two portions, place each portion into a Ziploc bag or wrap with plastic wrap, and refrigerate for at least 2 hours or overnight (refrigerating overnight is highly recommended).
Prepare the filling: In a medium bowl, mix the pumpkin puree, brown sugar, vanilla extract, and spices. If the filling is a bit liquid, you can thicken it by cooking it for a couple of minutes in a small pot.
Preheat the oven: Preheat your oven to 350°F (176°C). Line a baking sheet with parchment paper or a silicone mat and set aside.
Roll out the dough: On a floured surface, roll out one portion of the dough until it is approximately 3 mm thick. Lift and flip the dough occasionally to prevent it from sticking.
Cut the dough: Use a cookie cutter or a similar object to cut out circles of dough approximately 10 cm in diameter. Place on the baking sheet.
Fill the hand pies: Add about 1 tablespoon of the pumpkin filling to one half of each dough circle (forming a "D" shape), leaving a border of approximately 1 cm unfilled.
Seal the hand pies: Fold the dough circle in half, covering the filling to form a half-moon shape. Press the edges together with a floured or wet fork to seal the hand pie.
Glaze and bake: Brush the surface of the hand pies with agave or maple syrup. Bake for 40-45 minutes or until they are golden brown.
Cool and serve: Remove the hand pies from the oven and let them cool on a wire rack. If you want your hand pies to be shiny, brush another layer of syrup right away. Store the cooled hand pies in an airtight container at room temperature.