Prepare the Dough:
In a large bowl, combine the flour, sugar, and salt. Cut in the cold butter using a pastry cutter or your fingertips until the mixture resembles coarse crumbs. Gradually add ice-cold water, one tablespoon at a time, mixing until a dough forms. Shape into a disk, wrap in plastic, and chill for at least 1 hour.

Make the Ganache:
In a small saucepan, heat the heavy cream until it just begins to simmer. Remove from heat and pour over the chocolate chips (and cocoa powder, if using) in a bowl. Let sit for 2–3 minutes, then stir until smooth. Stir in a pinch of salt. Allow the ganache to cool and thicken slightly.

Assemble the Hand Pies:
Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper. On a lightly floured surface, roll out the dough to about 1/8-inch thickness. Using a round cutter (about 4–5 inches in diameter), cut out circles of dough.
Spoon about 1–2 teaspoons of the chocolate ganache into the center of each dough circle. Fold the dough over to form a half-moon shape and press the edges together with a fork to seal. Cut a small slit in the top of each pie to allow steam to escape.

Bake:
Brush each hand pie lightly with the beaten egg. Bake in the preheated oven for 20–25 minutes or until golden brown.

Finish & Serve:
Allow the hand pies to cool slightly on a wire rack. Dust with powdered sugar or drizzle with extra melted chocolate, and garnish with fresh raspberries or mint if desired. Enjoy warm or at room temperature.