Apple-Gruyère Slab Pie

Ingredients

• 3.75 cups flour
• 1.25 cups butter
• 1.5 cups shredded Gruyere cheese , divided
• 0.75 teaspoons salt
• 0.67 cups ice water
• 1 tablespoon cider vinegar
• 2 pounds Granny smith or other tart apples
• 2 pounds Jonathan or other sweet cooking apples
• 0.5 cups packed brown sugar
• 3 tablespoons cornstarch
• 3 tablespoons
• 2.5 teaspoons apple pie spice
• 2 teaspoons fresh thyme
• 0.13 teaspoons cayenne pepper , optional
• 1 large egg
• 1 tablespoon water
• coarse sugar
• vanilla ice cream , for serving
• cinnamon , for garnish

Instructions

1. 1

   Combine flour, 1 ¼ cups butter, 1/2 cup Gruyère, and the salt in a food processor; pulse until mixture resembles coarse crumbs, about 10 pulses. Combine ice water and vinegar in a small bowl; pour half into the food processor and pulse just until combined. Pour in remaining mixture; pulse until dough comes together, about 8 pulses. Divide dough in half. Shape into two (5x7-inch) rectangles. Wrap in plastic wrap and chill in the refrigerator for 30 minutes.

2. 2

   Combine apple slices, brown sugar, cornstarch, lemon juice, apple pie spice, thyme, cayenne (if using), and remaining 1 cup Gruyère in a very large bowl.

3. 3

   Preheat the oven to 375 degrees F (190 degrees C). Line a 10x15-inch rimmed baking sheet with parchment paper, extending parchment 2 inches over long sides of pan.

4. 4

   On a lightly floured surface, roll each pastry portion into a 13x18-inch rectangle; transfer 1 portion to the prepared baking sheet, easing pastry into the corners. Spoon filling over pastry in the baking sheet, spreading evenly. Cut 1-inch strips from remaining portion (if you like, twist strips) and arrange over the filling. Use any scraps to create a border; trim edges, if needed, press edges with fork tines to seal.

5. 5

   Beat egg and 1 tablespoon water together in a small bowl for the egg wash; brush onto top of pastry.

6. 6

   Bake in the preheated oven until golden and bubbly, 1 to 1 ¼ hours. Sprinkle generously with coarse sugar. Transfer pan to a wire rack; let cool 15 minutes. Use parchment to transfer pie from pan to a cutting board; cut into 16 pieces.

7. 7

   Serve warm or let cool completely. Serve with ice cream and garnish with cinnamon.