Cinnamon-Swirl Apple Slab Pie

Ingredients

• 3 tablespoons unbleached all-purpose flour, plus more for dusting
• 2 recipes Test Kitchen’s Favorite Pate Brisee, each shaped into a rectangular disk (recipe follows)
• 4 tablespoons unsalted butter, room temperature, plus 2 tablespoons, refrigerated and cut into small cubes
• ½ cup packed light-brown sugar
• 1 teaspoon ground cinnamon
• ½ teaspoon kosher salt
• 4 pounds assorted apples, such as Jonagold, Cortland, Granny Smith, and Empire, peeled, cored, and cut into ¼-inch slices
• 2 tablespoons fresh lemon juice
• 6 tablespoons granulated sugar
• 1 teaspoon pure vanilla extract
• 1 large egg, lightly beaten
• Fine sanding sugar, for sprinkling

For Test Kitchen's Favorite Pate Brisee:

• Makes enough for one 9-inch double-crust pie or one 10 ½-by-15 ¼-inch single crust slab pie
• 2 ½ cups unbleached all-purpose flour
• 1 ½ teaspoons coarse salt
• 1 tablespoon sugar
• 2 sticks (1 cup) cold unsalted butter, cut into small pieces
• 7 to 8 tablespoons ice water

Instructions

1. 1
   On a lightly floured surface, roll one disk of dough into a 12-by-17-inch rectangle. Transfer dough to a 10 1/2-by-15 1/4-inch rimmed parchment-lined baking sheet or jelly-roll pan and press into bottom edges and up sides. Fold overhang under and around edge. Refrigerate 30 minutes.
2. 2
   In a small bowl, combine room-temperature butter, brown sugar, cinnamon, and 1/4 teaspoon salt. On a lightly floured piece of parchment, roll second disk of dough into a 12-by-16-inch rectangle. Evenly spread butter mixture over dough all the way to ends, then, starting at a long edge, tightly roll into a log. Transfer to a baking sheet and refrigerate until firm, about 30 minutes.
3. 3
   Preheat oven to 425 degrees with a rack in lower third and a foil-lined baking sheet on a rack below. In a large bowl, toss together apples, lemon juice, granulated sugar, flour, remaining 1/4 teaspoon salt, and vanilla. Fill piecrust with apple mixture and dot with cold butter.
4. 4
   Cut dough log into 1/4-inch slices, rotating with each slice to keep slices round. (You'll need 63 slices total.) Arrange slices over apple mixture, slightly overlapping, in nine rows of seven. Refrigerate until firm, about 30 minutes.
5. 5
   Brush top of pie with egg wash and sprinkle with sanding sugar. Bake until top crust is just set, 20 minutes. Reduce temperature to 375 degrees and continue baking until crust is golden brown and juices are bubbling, about 1 hour. Let cool completely on a wire rack. Slab pie tastes best the day it's made.
6. 6
   Test Kitchen's Favorite Pate Brisee: Pulse flour, salt, and sugar in a food processor until combined. Add butter and pulse until mixture resembles coarse meal with some pea-size pieces remaining. Drizzle 5 tablespoons water over mixture; pulse several times to combine. Add more water, 1 tablespoon at a time, and pulse until mixture holds together when pinched.
7. 7
   For a 9-inch pie, shape dough into two disks and wrap each in plastic. For a slab pie, shape dough into a rectangle and wrap in plastic. Refrigerate at least 1 hour and up to 1 day or freeze up to 3 months; thaw overnight in refrigerator before using.