Roll Out the Dough: Cut the chilled dough in half, keeping one half wrapped in the fridge while you work with the other. On a lightly floured piece of parchment paper, roll the dough into an 8×12-inch rectangle, lifting and lightly flouring as needed to prevent sticking. Transfer the rolled dough (still on the parchment) to a baking sheet and refrigerate while you roll out the second half.
Cut Into Rectangles: Using a ruler, cut the dough into 8 equal rectangles, each about 3×4 inches (four across the long side and two across the short side). Repeat with the other sheet of dough. Gather and re-roll any scraps to make a few extra pies.
Whisk one egg with a splash of water to make the egg wash. Brush the edges of half of the dough rectangles with the egg wash.
Add Filling: Spoon 1–2 tablespoons of sweet potato filling into the center of each, spreading slightly but leaving a border where the egg wash is.
Seal and Crimp: Top each filled rectangle with another piece of dough. Gently press the edges together with your fingers to seal, then use a fork to crimp all sides. Cut a few small slits or holes in the top of each pie to allow steam to escape while baking.
Freeze: Place the assembled hand pies on a parchment-lined baking sheet, cover with plastic wrap, and freeze for at least 1 hour or overnight. (Freezing helps the pies hold their shape and ensures a perfectly flaky crust!)
When you’re ready to bake, preheat the oven to 375°F.
Make the Cinnamon Sugar: In a small bowl, mix together the granulated sugar and cinnamon.
Brush each frozen pie with egg wash on both sides. Roll or sprinkle generously with the cinnamon sugar until fully coated, then place them back on the parchment-lined baking sheet.
Bake for 20–25 minutes, or until golden brown and crisp. Let the pies cool slightly before serving. They’re best warm, but just as delicious at room temperature!