What causes flaky layers in a pie crust?
The flaky layers in a pie crust are created by solid chunks of butter layered within the dough. Rolling out the dough turns those butter pieces into thin sheets. And when the pie bakes, the sheets of butter melt and release steam, creating little pockets of air that lift and separate the crust into flaky layers.
The idea of keeping the butter cold to prevent it from fully incorporating into the dough is a great one and I highly recommend it.