16tablespoons (2 sticks)unsalted buttercold and cut into small pieces
For the apple pie filling
5largebaking apples (about 6 cups diced) (such as Granny Smith, Honeycrisp, Pink Lady, or Braeburn)
2tablespoonscornstarch
¼cupgranulated sugar
¼cupmaple syrup
1teaspoonground cinnamon
½teaspoonallspice
1 ½tablespoonsfresh lemon juice
Instructions
Preheat oven to 350°F. Grease a 10 x 14-inch baking pan (jelly roll-size pan) and set it aside.
Prepare the crust: In a large bowl, mix together the rolled oats, flour, brown sugar, granulated sugar, cinnamon, and kosher salt. Add the cubes of cold butter and toss with the dry ingredients. Work the butter into the dry mixture until it resembles wet sand with some pea-sized pieces of butter. Reserve 2 cups of the prepared crust and set it aside.
2 ¾ cups rolled oats, 1 ¾ cups all-purpose flour, ¾ cup light brown sugar, ½ cup granulated sugar, 1 teaspoon ground cinnamon, 1 teaspoon kosher salt, 16 tablespoons (2 sticks) unsalted butter
Form the crust: Firmly and evenly press the remaining crust into the prepared pan, pressing it up the sides. Bake the crust in the preheated 350°F oven for 15 minutes. Once baked, remove it from the oven and set aside to cool.
Prepare the filling: Peel, core, and cut the apples into cubes. In a large bowl, combine the prepared apples, cornstarch, granulated sugar, maple syrup, cinnamon, allspice, and lemon juice. Stir until well combined, then pour the mixture onto the baked crust.
5 large baking apples (about 6 cups diced) (such as Granny Smith, Honeycrisp, Pink Lady, or Braeburn), 2 tablespoons cornstarch, ¼ cup granulated sugar, ¼ cup maple syrup, 1 teaspoon ground cinnamon, ½ teaspoon allspice, 1 ½ tablespoons fresh lemon juice
Assemble: Spread the apples out into an even layer, overlapping as needed to fit all the apples. Sprinkle on the reserved 2 cups of prepared crust topping.
Bake in the 350°F preheated oven until the apples are tender, 35-45 minutes. Remove from the oven and cool for 1 hour before enjoying them!