3 cups unbleached all-purpose flour
1 cup plain bleached cake flour
6 1/2 sticks chilled unsalted butter
1 1/2 teaspoons salt
1 cup ice water

Place the flour in your mixing bowl. Rapidly cut the sticks of chilled butter into lengthwise quarters, then into 1/2-inch dice; add to the flour. Add the salt. Blend flour and butter together rapidly, the butter should be roughly broken up but stay in lumps the size of large lima beans. Blend in the water, mixing just enough so that dough masses roughly together but butter pieces remain about the same size. Turn dough out onto a lightly floured work surface. Rapidly push and pat and roll it out into a 12 by 18-inch rectangle. It will look messy.

Lightly flour top of dough and, with a pastry sheet to help you, flip the bottom of the rectangle up over the middle, and then flip the top down to cover it, as though folding a business letter. Lift the dough off the work surface with a pastry sheet; scrape the work surface clean, flour the surface lightly and return the dough to it, settling it down in front of you so that the top flap is at your right. Lightly flour top of the dough, and pat, push, and roll it out again into a rectangle; it will look a little less messy. Fold again into three as before, each of three "roll-and-fold" operations is called a "turn". Roll out and fold 2 more times, making 4 "turns" in all, and by the last "turn" of the pastry it should actually look like dough. You should see large flakes of butter scattered under the surface on the dough, which is just as it should be. With the balls of your fingers make 4 depressions in the dough to indicate the 4 turns. Wrap the dough in plastic, place in a plastic bag and refrigerate for 40 minutes to firm the butter and relax the gluten in the dough. Give the dough 2 more turns, beating it back and forth and up and down first if chilled and hard. Let the dough rest another 30 minutes if it seems rubbery and hard to roll; then it is ready for forming and baking.