Step 1 Place the flour on a cool work surface. Cut the butter lengthwise into 1/4-inch slices and lay them in the flour, flipping to coat with flour. Press each butter slice thin, pinching between your thumbs and fingertips. The slices will break into dimpled, cupped sheets, about 1/4- to 1/2-inch shards. You won't have incorporated much of the flour.
Step 2 Spread the pile into a lumpy, circular bed. Trickle ice water over it, stirring with your fingers as it puddles. If water starts to flow away, shove loose flour on the leak, then use a scraper to redirect the water to the dry mass.
Step 3Scrape in from the edges to roughly consolidate the mass. Slide the scraper under the mass and fold it over itself. Scrape up loose bits of dough; tuck them in the crack. Lift the mass, scraping it off the counter if necessary, then press flat enough to fold again. Repeat.
Step 4Continue pressing, scraping, lifting and folding 1 or 2 more times until all loose bits are incorporated and there are no major dry spots. You should see large sheets of butter and the surface should be mottled and dimpled. The dough should be soft; if it's dry, add up to another tablespoon of water and continue working it. If too moist, dust the work surface with another tablespoon of flour and work it in.
Step 5Wrap the dough loosely and refrigerate 30 minutes. Scrape the work surface clean.
Step 6Dust the work surface with 2 tablespoons of flour. (Try to use no more than this to finish the dough.) Roll out the dough, going toward and away from yourself, into a roughly rectangular shape about 1/2-inch thick. (Turning the dough over once or twice makes this easier to do.)
Step 7Fold the short ends of the dough in over itself in approximate thirds. Roll out as before and repeat. Rewrap loosely and refrigerate another 20 minutes. Scrape the work surface clean.
Step 8Roll and fold the dough in thirds 2 more times. The dough should be generally smooth but slightly streaky with a few discernable bits of butter. If the dough seems coarser, roll and fold it 1 or 2 more times. Wrap and refrigerate for at least 1 hour before the final rolling. Or wrap tightly and freeze for later use.