How to Make It
In a food processor, pulse the flour with the salt and 2 teaspoons of sugar. Add the butter and pulse until pea-size pieces form. Drizzle in the ice water as you pulse until the dough just comes together, about 1 minute. Turn the dough out onto a work surface and pat into a square about 1 inch thick. Wrap in plastic and refrigerate until firm, at least 1 hour or up to 2 days.
In a medium bowl, toss the nectarines with the blueberries, sugar, lemon juice, cinnamon, vanilla, ginger, nutmeg and salt. Sift the cornstarch over the fruit and stir until coated, making sure no clumps of cornstarch remain.
Preheat the oven to 375°. Line 2 large baking sheets with parchment paper. Cut the chilled dough in half. Work with 1 piece at a time and keep the other half chilled. On a lightly floured work surface, roll out the dough 1/8 inch thick. Using a 4-inch round cookie cutter, stamp out 8 rounds and arrange on one of the baking sheets, 2 inches apart. Refrigerate the rounds. Roll out the remaining dough 1/8 inch thick. Using a 4 1/2-inch round cookie cutter, stamp out 8 rounds; using a thin knife, cut three 1/2-inch slits in each round, then transfer to the second baking sheet.
Brush the edges of the 4-inch rounds with the egg wash. Using a slotted spoon, mound 1/3 cup of the fruit filling in the center of each round. Cover with the 4 1/2-inch rounds and crimp and seal the edges with a fork. Brush the pies with egg wash and sprinkle with sugar. Bake the pies for 30 to 35 minutes, until bubbling and deeply golden brown; rotate the baking sheets from top to bottom and front to back halfway through baking. Let the pies cool on the baking sheets for 10 minutes, then transfer to a rack and let cool before serving.