In a food processor, pulse together 2 cups of all-purpose flour and 1 cup of unsalted butter until the mixture resembles coarse crumbs, about 10-15 seconds. Add 1 egg yolk and 2 tablespoons of milk, blending until the dough starts to come together.

Transfer half the dough to your greased 13x9-inch pan, pressing it evenly across the bottom for the crust.

Peel and slice 4 cups of Granny Smith apples, then toss them in a large bowl with ½ cup granulated sugar, ¼ cup brown sugar, 2 tablespoons of flour, 1 teaspoon of cinnamon, and 1 teaspoon of vanilla extract. Mix well until all the apple slices are coated.

Evenly spread the apple filling over the prepared crust in the pan. Crumble the remaining dough over the apple filling.

Preheat your oven to 350°F (175°C) while you brush the top of the crumbled dough with an egg wash made from one beaten egg.

Sprinkle turbinado sugar over the top for an extra crunch and a sweet finish.

Place the assembled bars in your preheated oven and bake for 35-40 minutes. Keep an eye on them towards the end to ensure they don’t over-brown.

Once baked, remove the pan from the oven and let your Flaky Apple Pie Bars cool completely in the pan on a wire rack.

After about 30 minutes, cut into squares or bars and serve.