Lay out three-quarters of the butter pieces on a parchment-lined baking sheet, and freeze until hard, at least 30 minutes. Refrigerate remaining butter.
Combine flour, salt, and sugar in a food processor. Add refrigerated butter, and pulse to combine, about 10 times. Add frozen butter, and pulse until mixture resembles coarse meal, with some blueberry-size clumps.
Add ice water, and immediately pulse until water is just incorporated, about 10 times. Squeeze a small amount of dough to make sure it holds together. Pulse a few more times if needed.
Lay out 2 pieces of plastic wrap. Empty half the dough onto each piece. Bring edges of wrap together to gather dough. Press into disks.
Roll out disks, still wrapped in plastic, to 1/2-inch-thick rounds (8 inches in diameter). Refrigerate at least 45 minutes and up to 2 days. Dough can be frozen up to 1 month.
Some large clumps (about the size of small blueberries) should remain after pulsing the butter with the dry ingredients. The finished dough should be mottled with large pieces of butter. The best way to transfer the rolled-out dough to a pie plate is by rolling it over the pin and unfurling it onto the plate.