Cream Cheese Pie Dough
In a medium sized bowl, combine the flour and salt thoroughly. Add the cream cheese pieces to the mixing bowl and combine until the mixture resembles cornmeal. Add the butter pieces and cut in with a pastry blender or by rubbing your fingers together through the mixture until it appears rough, with pieces like the size of peas. Sprinkle the ice-cold water and the lemon juice over the mixture and mix until just combined. Continue to mix until dough is rough but pliable. The dough should hold together when pressed to the side of the bowl, and not form a ball in the bowl. Turn out the dough onto a lightly floured work surface. Form dough into a 5-6 inch disc and wrap tightly with plastic wrap. Refrigerate at least 1 hour, preferably overnight, until firm.
Blueberry Filling
Preheat oven to 375°F and set the rack in the lowest position. Line a baking sheet with parchment paper.
In a medium saucepan, combine the blueberries, sugar, cornstarch, lemon juice, lemon zest and salt; stir to combine. Bring to a gentle simmer over medium heat, and cook, stirring, until the juices are thickened and clear, 2-3 minutes. Remove the pan from the heat and allow to cool to room temperature, about 30 minutes.
Roll out the chilled dough to 1/8 inch thick. Using a round 4 ½ inch cutter, cut 8 discs from the dough, re-rolling scraps as necessary. Transfer the discs to prepared baking sheet and refrigerate for 10 minutes. Remove the dough discs from the refrigerator. Place 1 tablespoon of the filling in the center of a disc. Lightly brush water around the edge of half of the disc, and then fold the other half over the filling to create a half-circle. Seal and add a decorative border by pressing the edges of the dough together with the tines of a fork. Repeat with remaining dough discs and filling.
Place the hand pies on a prepared baking sheet and brush them with egg wash. Using a paring knife, cut a few steam vents into the top of each pie. Bake until filling is bubbly and thick and the crust is golden brown, 20-25 minutes. Remove from the oven and place them on a cooling rack. Let cool completely before drizzling glaze over the top with a fork.
Lemon Icing Glaze
In a small bowl, mix together confectioners' sugar and vanilla. Add the lemon juice, then the milk, and stir to combine. If necessary, add more milk, 1 teaspoon at a time, until the glaze is smooth and fluid.
Alternate Instructions for Cream Cheese Pie Dough
In the bowl of a stand mixer fitted with the paddle attachment, combine the flour and salt thoroughly. With the mixer off, add the cream cheese pieces to the mixing bowl and combine on medium speed until the mixture resembles cornmeal. Add the butter pieces and combine until the mixture appears rough, with pieces like the size of peas. Sprinkle the ice-cold water and the lemon juice over the mixture and mix on low speed until just combined. Continue to mix until dough is rough but pliable. The dough should hold together when pressed to the side of the bowl, and not form a ball in the bowl. Turn out the dough onto a lightly floured work surface. Separate the dough in half, then each piece into a 5-6 inch disc and wrap tightly with plastic wrap. Refigerate at least 1 hour, preferably overnight, until firm.