Roll the bottom crust to a 1/8 of an inch thick 13 inches circle then transfer to a 9 inches pie pan. Fold under the excess and crimp the border. Refrigerate for a minimum of 1 hour.
Remove from fridge, line with parchment and fill with dried beans, rice or weights.
Bake for 20 mines. Lift the parchment and the beans. Prick the bottom with a fork and bake 5 to 10 minutes more. Cool the crust on a rack. you can then if you like brush the crust with egg white for added protection.
Measure 1 cup of blueberries and put them in a saucepan with 1/2 cup of water. Bring to a boil.
Meanwhile, in a small bowl whisk cornstarch and the 2 tablespoons of water and set aside.
When the water and blueberries have come to a boil, simmer for 3 minutes then add the cornstarch mixture, lemon juice and salt, simmer for a couple of minutes, remove from heat and add to the 3 cups of fresh blueberries.
Spoon the mixture in the baked shell and allow to sit room temperature for at least 2 hours before serving.
Can be served with mascarpone cream, whipped cream or creme patisserie.
Store up to 3 days room temperature.