Squeeze the pulp from the grapes into a medium pot, reserving the skins. Transfer the skins to a food processor.
Set the pot over medium hear and cook, stirring occasionally, until the mixture comes to a simmer. Continue to cook until the grapes have broken down and released their juices, about 10 minutes.
While the pulp cooks, pulse the skins and the lemon juice in the food processor to coarsely chop them. Set aside.
Once the pulp mixture is fully broken down, strain it into a medium bowl, firmly pressing on the sieve to extract all of the juice. Discard the seeds that remain.
Transfer the mixture back to the pot and add the chopped skins and the cinnamon stick. Bring to a gentle simmer over medium-low heat and then reduce the heat to low and simmer for 5 minutes, stirring occasionally.
Meanwhile, in a medium bowl, rub the vanilla bean seeds and sugar together to combine. Whisk in the cornstarch and salt, then sprinkle the mixture over the grape mixture and stir well to combine. Allow the mixture to simmer for 1 minutes, stirring constantly.
Transfer the filling to a large bowl to cool completely. (The grape mixture will cool faster if spread out on a rimmed baking sheet.) Cover with plastic wrap pressed against the surface to prevent a skin from forming.
To Make the Pie Crust:
In a large bowl, whisk together the flour and salt to combine. Add the butter, tossing the cubes in the flour to coat. Working quickly, using a pastry cutter or your fingers, cut the butter into the flour until the butter is about the size of walnut halves.
Make a well in the center and add the water a few tablespoons at a time, and mix just until the dough comes together. Continue adding water a tablespoon at a time until you have a dough that holds together well but isn’t wet or sticky. (About 8 tablespoons total)
Divide dough in half and shape each one into a round disc about 1-inch thick. Wrap both halves in plastic and refrigerate for at least 1 hour.
To Assemble the Hand Pies:
Line two baking sheets with parchment paper and set aside.
On a lightly floured surface, roll out one portion of the pie dough until it's about ¼-inch thick. Using a 3-inch round pastry cutter, cut out circles of the pie dough and place onto the parchment-lined baking sheet; you should have a total of 15 circles. Place in the fridge until needed and repeat the process with the second portion of the pie dough.
Spoon about ½ tablespoon of the filling into the center of each circle of dough. Brush the edges of each circle with egg wash and place one of the remaining pieces of dough on top of it. Use a fork to crimp the edges to seal.
Repeat the process with the remaining dough and jam. Chill the tray of assembled hand pies in the refrigerator for 30 minutes.
Preheat the oven to 400°F (205°C).
Brush the pies with egg wash (avoid brushing too much on the edges, which will brown more on their own) and sprinkle generously with turbinado sugar. Cut a small slash or X in the top of each pie with the tip of a paring knife.
Bake for 20-25 minutes, until deeply golden brown. Allow to cool completely before serving or filling with ice cream.
Flip half of the hand pies upside down so their base is facing upward. Using a serrated knife, cut each pint of ice cream into even pieces. Place each slice on top of one of the upside-down hand pies, and top with another cooled hand pie (sugared side up). Freeze the assembled sandwiches immediately. Keep frozen until ready to serve.
* Feel free to use a high-quality grape jam or jelly instead!