Melt 2 tablespoons butter in a medium skillet over medium heat. Add the finely diced apples, brown sugar, cinnamon, nutmeg, and vanilla extract.

Sauté for 6 to 8 minutes until the apples are tender but still retain a pleasant slight bite. Stir in the cornstarch slurry and cook for 1 minute until juices turn thick and glossy. Remove from heat and stir in the salted caramel sauce. Let cool completely before assembling pies.

Preheat oven to 375°F (190°C). Line two large baking sheets with parchment paper.

Unroll the chilled pie crust dough onto a lightly floured surface. Using a 4-inch round cutter (or cutting into 3.5x4.5 inch rectangles), cut out 16 dough pieces (re-rolling scraps as needed).

Spoon about 2 tablespoons of cooled caramel apple filling onto the center of 8 dough rounds. Lightly brush edges with egg wash.

Place the remaining 8 dough rounds over the filling. Press firmly around the edges to seal, then use the tines of a fork to crimp the borders decoratively.

Cut two small vent slits in the top of each hand pie with a sharp knife to allow steam to escape.

Brush the tops of the assembled hand pies generously with egg wash. Sprinkle liberally with coarse turbinado sparkling sugar.

Bake at 375°F (190°C) for 22 to 25 minutes, until the pastry crusts are puffed, deeply golden-brown, and the filling begins bubbling gently at the vent slits.

Transfer to a wire cooling rack and let cool for 15 minutes.

Whisk powdered sugar, milk, and vanilla together until smooth. Drizzle vanilla glaze and warm salted caramel across the warm hand pies and serve.