Apple Pie Bars
3 Sticks Butter, Softened
3/4 Cup Sugar
3 Cups All-Purpose Flour
6 Tablespoons Butter
1/2 Cup Light Brown Sugar
12 Granny Smith Apples (About 6 Pounds)—Peeled, Cored And Thinly Sliced
1 Tablespoon Cinnamon
1/4 Teaspoon Freshly Grated Nutmeg
1 Cup Water, As Necessary
3/4 Cup Walnuts
3 Cups Quick-Cooking Oats
2 Cups All-Purpose Flour
1 1/2 Cups Light Brown Sugar
1 1/4 Teaspoons Cinnamon
1/2 Teaspoon Baking Soda
1/2 Teaspoon Salt
3 Sticks Butter, Cut Into 1/2-Inch Cubes And Chilled
Make the crust: Preheat the oven to 375°. Line a 15-by-17-inch rimmed baking sheet or jelly roll pan with parchment paper.
In a large mixing bowl, beat the butter with the sugar at medium speed until light and fluffy, about 2 minutes. At low speed, beat in the flour until a soft dough forms. Press the dough over the bottom of the prepared pan and 1/2 inch up the side in an even layer. Bake in the center of the oven for about 20 minutes, until the crust is golden and set. Let cool on a rack.
Filling: In a large pan, melt 3 tablespoons of the butter with 1/4 cup of the light brown sugar. Add the apples and cook over high heat, stirring occasionally, until softened, about 10 minutes. Stir in the cinnamon and nutmeg. Cook until the apples are caramelized and very tender and the liquid is evaporated, about 10 minutes longer; scrape up any bits stuck to the bottom and add up to 1/2 cup of water to pan to prevent scorching. Let cool.
Topping: Spread the walnuts in a pie plate and toast until golden and fragrant, about 8 minutes. Let cool, then coarsely chop the walnuts. In a large bowl, mix the oats with the flour, light brown sugar, cinnamon, baking soda and salt. Using a pastry blender or two knives, cut in the butter until the mixture resembles coarse meal. Stir in the walnuts and press the mixture into clumps.
Spread the apple filling over the crust. Scatter the crumbs on top, pressing them lightly into an even layer. Bake in the center of the oven for 1 hour, until the topping is golden; rotate the pan halfway through baking. Let cool completely on a rack before cutting into 2-inch bar
4 dozen bars