Special equipment: One 9-inch Pyrex pie pan or 6 or 8 individual pans
Prepare dough: To mix the dough by hand, combine the dry ingredients in a medium mixing bowl and stir well to combine. Cut the butter into 1-tablespoon pieces and add to the dry ingredients. Toss once or twice to coat the pieces of butter. Then using your hands or a pastry blender, break the butter into tiny pieces and pinch and squeeze it into the dry ingredients. Occasionally reach down to the bottom of the bowl and mix all the ingredients evenly together. Continue rubbing the butter into the dry ingredients until the mixture resembles a coarse-ground cornmeal and no large pieces of butter remain visible. Beat the eggs in a small bowl and pour over the flour and butter mixture. Stir in with a fork until the dough begins to hold together but still appears somewhat dry. Scatter a teaspoon of flour on the work surface and scrape the dough out onto it. Press and knead the dough quickly 3 or 4 times, until it is smooth and uniform.
To mix the dough in the food processor, combine the dry ingredients in the work bowl fitted with a metal blade. Pulse 3 times at 1-second intervals to mix. Cut the butter into 1-tablespoon pieces and add to the work bowl. Process, pulsing repeatedly at 1-second intervals, until the mixture is fine and powdery, resembles a coarse-ground cornmeal, and no large pieces of butter remain visible, about 15 pulses in all. Add the eggs to the work bowl and pulse 10 times or so, until the dough forms a ball. Scatter a teaspoon of flour on the work surface and scrape the dough out onto it. Press and knead the dough quickly 3 or 4 times, until it is smooth and uniform.
Press the dough into two equal-sized disks. Sandwich the disks of dough between two pieces of plastic wrap and press them into 6-inch circles. Refrigerate the dough until firm, or until you are ready to use it, at least 1 hour.
To make the filling, combine 1 cup of the blueberries with the sugar in a non-reactive saucepan. Bring to a simmer over low heat, stirring occasionally, until the sugar is melted and the mixture is very liquid -- about 5 minutes. Combine the cornstarch and water in a small bowl and whisk the blueberry and sugar mixture into it. Return everything to the pan and cook, stirring constantly, over low heat, until the mixture comes to a boil, thickens and becomes clear. If it does not become clear, continue to cook over low heat for a few more minutes, until it does. Pour into a large bowl and stir in the remaining filling ingredients, except the blueberries, then add the remaining 3 cups blueberries. Cool.
Set a rack at the upper and lower thirds of the oven and preheat to 400 degrees. Roll out the bottom crust and arrange in pan, or pans. Trim edge even with rim of pan. Pour the cooled filling into the bottom crust. Roll remaining dough into a rectangle and cut 8 small strips to finish the top of each pie. Apply the strips, severing excess dough at edge of pans, 4 in each direction, diagonal to each other. If you wish, sprinkle the top of the pie with sugar.
Place the pie in the oven on the lower rack and reduce the temperature to 375 degrees. Bake for about 40 minutes, until the crust is baked through and a deep golden brown and the filling is gently bubbling. If the top crust has not colored sufficiently after 30 minutes of baking, move the pie to the upper rack of the oven for the last 10 minutes. Cool the pie on a rack.
Hints: Always pass a small bowl of extra whipped cream at the table when serving a dessert with whipped cream. Rinse blueberries in a colander, then place on a jelly roll pan covered with paper towels to drain; pick over to remove shriveled berries, leaves and stems.