Two key elements to a classic apple pie are a double crust and perfectly cooked, lightly sweetened and cinnamon-kissed apples. To achieve this, we honed in on the right combination of butter, shortening and ice water in the crust and gave the pastry plenty of time to hydrate in the refrigerator. For the filling: quickly cooking the apples before going in the pie ensures they will be soft but with a slight bite once cooked and there will not be a huge air gap between the fruit and top crust.
Make the filling: Toss the apples with the granulated sugar and lemon juice in a bowl. Melt the butter in a large skillet over medium-high heat. Add the apples and cook, stirring, until the juices are simmering. Reduce the heat to medium and cook, stirring, until the firmer apples soften but still hold their shape, 6 to 8 minutes. Sprinkle in the flour, cinnamon and salt and toss to thicken the juices, about 1 minute. Remove from the heat and let cool. (The filling can be made up to 2 days ahead; cover and refrigerate.)
Make the crust: Pulse the flour, baking powder, granulated sugar and salt in a food processor. Add the shortening and 4 tablespoons butter; pulse until the mixture looks like coarse meal. Add 6 more tablespoons butter and pulse until pea-size pieces form. Add 3 tablespoons ice water and pulse a few times. If the dough doesn’t hold together when squeezed, add more ice water, 1/2 tablespoon at a time. Divide the dough between 2 sheets of plastic wrap and pat each into a disk. Wrap and refrigerate until firm, at least 3 hours or up to overnight.
Roll out 1 disk of dough on a lightly floured surface (or between 2 sheets of floured parchment) into a 12-inch round. (If the dough gets too warm, refrigerate until firm.) Ease into a 9-inch pie plate. Add the filling, mounding it slightly in the center, and dot with the remaining 2 tablespoons butter. Transfer the pie to the refrigerator.
Roll out the remaining dough into a 12-inch round. Lay the dough over the filling and press the 2 crusts together around the edges. Fold the overhanging dough under itself and crimp as desired. Brush the beaten egg over the top crust and edge; sprinkle with the turbinado sugar. Pierce the top crust with a knife a few times to let steam escape. Refrigerate 1 hour.
Put a rimmed baking sheet on the bottom oven rack and preheat to 425˚ F for 30 minutes. Place the pie on the hot pan and reduce the oven temperature to 375˚ F. Bake until the crust is golden and the filling is bubbly, 1 hour 10 minutes to 1 1/2 hours; rotate the pie as needed and cover with foil if the crust browns too quickly. Transfer to a rack to cool completely.