Granny Smith Slab Pie

Step 1

Prepare the Crust: Preheat oven to 375°F. Pulse together flour, sugar, and salt in a food processor until combined, 5 to 8 pulses. Add butter, and pulse until mixture is crumbly, about 10 pulses. With food processor running, add 3/4 cup cold water in a slow steady stream until mixture just forms a dough, about 45 seconds. Divide dough in half; shape each dough half into a square, and wrap tightly in plastic wrap. Refrigerate until firm, about 30 minutes.

Step 2

On a lightly floured surface, roll 1 dough square into a 15- x 12-inch rectangle, about 1/8-inch thick. Transfer to a 13- x 9- x 1-inch baking pan, pressing into corners and letting dough hang over sides of pan. Refrigerate, uncovered, while preparing filling.

Step 3

Prepare the Filling: Combine apples, granulated sugar, cornstarch, lemon juice, apple pie spice, and salt in a large bowl until combined. Spread mixture over chilled pie crust. Sprinkle evenly with cubed butter.

Step 4

On a lightly floured surface, roll out remaining dough square to a 15- x 12-inch rectangle, about 1/8-inch thick; drape dough over filling. Fold edges under, and crimp as desired. Freeze for 10 minutes. Cut about 24 (2-inch) diagonal slits across top of pie. Whisk together egg yolk and 1 tablespoon water in a small bowl. Brush crust with egg wash, and sprinkle with turbinado sugar.

Step 5

Bake in preheated oven until crust is golden brown and filling is bubbly, 55 to 65 minutes. If crust begins to brown too quickly, loosely tent pie with aluminum foil. Transfer to a wire rack, and let cool, about 1 hour.

Step 6

Whisk together powdered sugar, whipping cream, and maple syrup in a small bowl until smooth. Drizzle over slightly cooled pie before serving.