Ingredients:
Pastry
1 1/2 cups(180 grams) all-purpose flour
1 cup(99 grams) spelt flour
1 teaspoongranulated sugar
1 teaspoonkosher salt
1/4 teaspoonground cayenne
1 cup(8 ounces/2 sticks) unsalted butter, cubed, frozen for 15 minutes
1/4 cupapple cider vinegar
1/4 cupice water
Filling
3 tablespoonsunsalted butter
3 small crisp, tart apples (such as Braeburn, Stayman Winesap, or Granny Smith)
1 teaspoonground cinnamon
1 teaspoonground ginger
1/2 teaspoonfreshly grated nutmeg
1 pinchkosher salt
3 tablespoonstightly packed brown sugar
Zest from 1 lemon
1 tablespoonfreshly squeezed lemon juice
2 dashesangostura bitters
1 teaspooncornstarch
Buttermilk (or milk or cream), for brushing
1/4 cupDemerara sugar, for sprinkling
Directions:
Make the dough: In a food processor, pulse the flours, sugar, salt, and cayenne to combine. Add the butter and pulse until the pieces are pea-sized. Combine the vinegar and ice water. Slowly drizzle in half while pulsing the food processor until a shaggy dough forms. Pause and test by squeezing a clump between your fingers—if it holds, the dough is ready. If it is still crumbly, drizzle a little more of the liquid while pulsing, then test again. Evenly divide the dough between two pieces of plastic wrap. Use the wrap to shape one portion into a rectangle and tightly seal. Pat the second one into a disk and save for another use. Refrigerate the dough for at least 20 minutes or up to 3 days (you may freeze the second disk, up to 3 months).
Onto the filling: Melt the butter in a heavy, 9-inch skillet over medium heat. Once foaming subsides, cook until the butter is honey-colored and smells nutty, about 5 minutes, occasionally swirling the pan to prevent burning.
While the butter is browning, peel, halve, and core apples, then cut into ¼-inch-thick slices.
Add the apple slices to the brown butter, toss to coat, and cook for 2 minutes, until they take on some of the browned bits. Add the cinnamon, ginger, nutmeg, and salt and stir to coat. Now add the brown sugar and stir again. Add the lemon zest, followed by the juice, bitters, and cornstarch and stir. Gently press the apples into an even layer and cook for about 5 more minutes, until the apples are soft but still intact. Remove the pan from the heat. Taste an apple slice and adjust the seasoning if needed. Allow them to cool to room temperature, then transfer to an airtight container and refrigerate. This step can be done 1 day in advance.
Roll out the dough: Roll the dough rectangle to ⅛ inch thick, about 18×11 inches. (I like to do this by flouring a piece of parchment, unwrapping the dough, flouring it, placing it on the parchment, then placing a piece of plastic on top.) If the dough becomes smeary or flabby at any point, chill in the refrigerator for 10 to 20 minutes.
Use a 3-inch round biscuit or cookie cutter and make 12 cutouts in the dough. Arrange them on a parchment-lined sheet pan. Reroll scraps into a 9×6-inch rectangle (or similar), then cut into ¼-inch-wide strips along the long edge. Arrange these on a parchment-lined plate or small tray and refrigerate.
Evenly divide the apple slices between the 12 circles.
Cut the long strips into 3-inch lengths. Lay 4 lengths per cookie in a square frame. Dab the ends where they overlap with a little water to affix. Holding a cookie in your hand, roll the bottom pastry edge all the way around, making a tidy border and sealing in the lattice edges. Repeat with the remaining cookies.
Lightly paint each pastry surface with buttermilk, then sprinkle Demerara sugar onto each (½ teaspoon or so per cookie).
Freeze the cookies for at least 30 minutes or up to 4 hours.
When you’re ready to bake, heat the oven to 400°F. Line a second sheet pan with parchment. Divide the cookies between the two sheets, spacing them far apart from one another. Bake for 25 minutes, until the crust is golden. After 15 minutes, rotate the pans and check the pastry—you can cover any especially dark pastry with foil strips as needed.
Cool the cookies on a wire rack to room temperature. Store any leftover cookies at room temperature, wrapped in foil, for up to 2 days.