FOR THE PATE BRISEE, stir the flour and sugar together in a mixing bowl. Cut the chilled butter into small pieces and drop into the flour. With your fingers, lightly and quickly rub the butter and flour together until the mixture becomes crumbly, or cut it in with a knife or pastry cutter. Whisk together the egg yolk, lemon juice, and 1 tablespoon of water. Sprinkle the liquid over the butter-flour mixture and continue to stir or rub this mixture between your fingers until a ball of dough forms. Be careful not to overwork the dough. If the mixture is crumbly, add up to one more tablespoon water, sprinkling it over the dough and lightly kneading it into a ball. On a floured board and with a floured rolling pin, roll out the dough into a large circle. Gently lift it into a 9or 25 cm pie plate or tart tin. Patch any holes in the crust with bits of dough and trim the edges. Flute the crust. Chill for 2 hours. Preheat the oven to 190ºC . Place a sheet of aluminum foil in the bottom of the crust and fill it with dried beans or rice to weigh it down during baking. Bake for 15 minutes. Remove the crust from the oven and carefully lift out the foil and beans. Bake for 5 minutes more. Cool. TO MAKE THE FILLING, heat in a small saucepan 2 cups of the blueberries, 2 tablespoons of water, and the sugar. Crush a few berries with a spoon to release the juice. When the berries have softened and become juicy, add the cornstarch mixture. Simmer on low heat for about 10 minutes, stirring occasionally, until the mixture thickens. Remove it from the heat and fold in one more cup of blueberries. Pour the berry mixture into the baked pie shell. Top with remaining 2 cups blueberries. Cool for at least one hour. Serve plain or topped with fresh whipped cream, if desired, or sweetened Creme Fraiche.