The secrets to flaky pie crusts are. . .
Anyhow, Kung Foodie asked: "And the gallette pastry secret is...?"
To be honest, it's not one secret; it's a confluence of secrets that synergistically enhance each other's effects until the combined secret has a qualitatively distinct benefit that can justifies calling the act of combining of all these secrets itself a secret.
The "secret" as taught by Peter in his explanation of the scientific theory of flaky crusts is that the butter must be cut to chunks of optimum size: about the size of a pea. (And I mean butter, not margarine, not shortening. Real butter.) When the dough is kneeded, the chunks flatten out, and separate layers of pastry; when the dough is baked, the butter melts and is absorbed into the pastry, leaving a thin cavity of separation between layers of dough, which the pie-eater perceives as that wonderful flakiness.
To keep the butter chunks cold so they don't melt in your hands while you work the dough, mix your flour, salt, and sugar ahead of time, put it in a snap-lid plastic container, and freeze the powdered mix. Never freeze the butter: it becomes unworkable.
And lastly, the secret I came up with: instead of using a pastry cutting tool (a.k.a. "dough blender") to incorporate the butter, I cut all of the butter to pea sized balls by using an egg slicer. I opened it up and used the wire grate to slice the butter into pats, and then I dusted the pats with flour to keep them from sticking to each other, stacked the pats and used the cutter to cut the pats into sticks. After dusting with flour again, I cut the sticks into cubes. Each one was about the size of a pea simply due to the width of the wires on the egg slicer. Then, I mixed the butter cubes with the frozen flour/salt/sugar mix, added some egg and water beaten together, and squished the little butter cubes into flat disks as I kneeded the dough. When the pie was assembled, I brushed the upper surface with some egg white and sprinkled brown sugar on it to get that crunchy sugared surface.
There you have it: the secret to my pie crust. Enjoy!