In a food processor, combine all-purpose flour, kosher salt, and granulated sugar; pulse until well combined. Add cubed cold unsalted butter, pulsing until crumbly. Drizzle in ice water gradually, pulsing until the dough holds together. Form into disks, wrap in plastic, and refrigerate for 2 hours.

In a saucepan over medium heat, bring whole milk, vanilla extract, and coconut extract to a boil, stirring occasionally. In a bowl, whisk egg yolks, granulated sugar, cornstarch, and kosher salt until smooth. Gradually pour in hot milk while whisking. Return to saucepan, cook for 5–7 minutes until thickened. Stir in sweetened coconut and butter, then refrigerate for 1 hour.

Preheat oven to 375°F (190°C) and line baking sheets with parchment paper. Roll out chilled dough to ⅛ inch thick. Use a 4-inch cutter to cut circles and place a tablespoon of filling on one side of each circle. Brush edges with beaten egg, fold over, and seal with steam vents.

Transfer sealed pies to baking sheets, spaced apart. Bake for 22–25 minutes until golden brown. Cool on a wire rack for 10 minutes until completely cooled.

Melt semisweet chocolate in a microwave-safe bowl, stirring every 30 seconds. Drizzle over cooled hand pies and optionally sprinkle toasted coconut on top.