In a mixing bowl, stir together flour and salt. Using a pastry blender or a fork(or let your kids mix it), cut in shortening and butter until mixture resembles coarse meal.
Add the vinegar. Sprinkle ice water over flour mixture 1 tablespoon at a time, mixing lightly with a fork, just until pastry holds together. Wrap the ball of pastry with saran wrap tightly then put it in the fridge for an hour or so.
In a bowl, gently stir together the fresh blueberries, sugar, flour, lemon juice, and ground cinnamon. Set it aside.
Take the pastry out of the fridge, cut in half.
Flatten 1 half on top of a floured surface. Roll the dough until it’s about 12-inch circle about 1/8-inch thick.
Wrap the dough into the pin and slowly unroll into the baking pan. Smooth the dough out.
Stab the dough with fork. Whisk the egg white until slightly frothy. Brush the dough with it. Then evenly add the blueberry mixture on top.
Roll the other half of the dough like the first one. Let your kids use cookie cutters to cut out shapes.
Preheat the oven to 375°. Place the cut out dough on top of the pie. Decorate however you like.
Beat the egg yolk, brush the top with the egg wash then sprinkle sugar on top. Cover a sheet pan with foil, place the pie into the pan then bake it in the oven for 45minutes.
