1. Cut the butter into small (about 3/4-inch) cubes. Wrap it in plastic wrap and freeze it until frozen solid, at least 30 minutes. Place the flour, salt, and baking powder in a reclosable gallon-size freezer bag and freeze for at least 30 minutes.
2. Place the flour mixture in a food processor with the metal blade and process for a few seconds to combine. Set the bag aside.
3. Cut the cream cheese into 3 or 4 pieces and add it to the flour. Process for about 20 seconds or until the mixture resembles coarse meal. Add the frozen butter cubes and pulse until none of the butter is larger than the size of peas; toss with a fork to see it better. Remove the cover and add the water and vinegar. Pulse until most of the butter is reduced to the size of small peas. The mixture will be in particles and will not hold together. Spoon it into the plastic bag and for a double pie crust divide the mixture in half at this point.
4. Holding both ends of the bag opening with your fingers, knead the mixture by alternately pressing it from the outside of the bag with the knuckles and heels of your hands until the mixture holds together in one piece and feels slightly stretchy when pulled.
5. Wrap the dough in plastic wrap, flatten it into a disk, and refrigerate it for at least 45 minutes and preferably overnight.
6. Remove the dough for the bottom crust from the refrigerator. If necessary, allow it to sit for about 10 minutes or until it is soft enough to roll.
7. On a floured pastry cloth or between two sheets of lightly floured plastic wrap, roll the bottom crust 1/8-inch thick or less and 12 inches in diameter. Transfer it to a 9-inch pie pan. Trim the edge almost even with the edge of the pan. Cover it with plastic wrap and refrigerate it for a minimum of 30 minutes and a maximum of 3 hours.
8. In a large bowl, combine the apples, lemon juice, sugars, cinnamon, nutmeg, and salt and toss to mix. Allow the apples to macerate at room temperature for a minimum of 30 minutes and a maximum of 3 hours.
9. Transfer the apples and their juices to a colander suspended over a bowl to capture the liquid. The mixture will release at least 1/2 cup of liquid.
10. In a small saucepan (preferably nonstick), over medium-high heat, boil down this liquid, with the butter, to about 1/3 cup (a little more if you started with more than 1/2 cup of liquid), or until syrupy and lightly caramelized. Swirl the liquid but do not stir it. (Alternatively, spray a 4-cup heatproof measure with nonstick vegetable spray, add the liquid and butter, and boil it in the microwave, 6 to 7 minutes on high.) Meanwhile, transfer the apples to a bowl and toss them with the cornstarch until all traces of it have disappeared. Pour the syrup over the apples, tossing gently. (Do not be concerned if the liquid hardens on contact with the apples; it will dissolve during baking.)
11. Roll out the top crust large enough to cut a 12-inch circle. Use an expandable flan ring or a cardboard template and a sharp knife as a guide to cut the circle.
12. Transfer the apple mixture to the pie shell. Moisten the border of the bottom crust by brushing it lightly with water and place the top crust over the fruit. Tuck the overhang under the bottom crust border and press down all around the top to seal it. Crimp the border using a fork or your fingers and make about 5 evenly spaced 2-inch slashes starting about 1 inch from the center and radiating toward the edge. Cover the pie loosely with plastic wrap and refrigerate it for 1 hour before baking to chill and relax the pastry. This will maintain flakiness and help to keep the crust from shrinking.
13. Preheat the oven to 425 degrees at least 20 minutes before baking. Set an oven rack at the lowest level and place a baking stone or baking sheet on it before preheating. Place a large piece of greased foil on top to catch any juices.
14. Set the pie directly on the foil-topped baking stone and bake for 45 to 55 minutes or until the juices bubble through the slashes and the apples feel tender but not mushy when a cake tester or small sharp knife is inserted through a slash. After 30 minutes, protect the edges from overbrowning by covering them with a foil ring.
15. Cool the pie on a rack for at least 4 hours before cutting. Serve warm or at room temperature.
From The Pie and Pastry Bible, by Rose Levy Beranbaum.
"Often you find that there are ways you can improve techniques or recipes," says J. Kenji López-Alt, author of The Food Lab: Better Home Cooking Through Science.