Prepare the crust: In a large bowl, combine the flour, sugar, and salt. Add the cold, cubed butter and use a pastry cutter or your fingers to work the butter into the flour until the mixture resembles coarse crumbs. Gradually add ice water, one tablespoon at a time, until the dough comes together. Divide the dough into two discs, wrap in plastic wrap, and refrigerate for at least 30 minutes.

1. Make the cherry filling: In a medium saucepan, combine cherries, sugar, lemon juice, cornstarch, vanilla extract, and salt. Cook over medium heat, stirring frequently, until thickened (about 8-10 minutes). Remove from heat and let cool.
2. Roll out the dough: Preheat oven to 375°F (190°C). Roll out one disc of dough on a floured surface to about ¼ inch thick. Cut heart shapes using a cookie cutter. Repeat with the second disc.
3. Assemble the hand pies: Place a spoonful of cherry filling in the center of one dough heart. Top with another dough heart and press edges together gently. Crimp with a fork to seal and cut a small slit on top for steam.
4. Apply the egg wash: Mix egg and water in a small bowl. Brush the tops of the hand pies with the egg wash.
5. Bake the pies: Place hand pies on a parchment-lined baking sheet. Bake for 20-25 minutes or until golden brown and filling is bubbling.
6. Cool and serve: Let cool for a few minutes before serving. Enjoy warm or at room temperature.