Flaky Apple Pie Bars

Preheat oven to 400°F.

Unfold puff pastry and place on a large rimmed baking sheet. With a sharp knife, gently score the pastry about ¼ inch from the edge to create a border.

Combine apples, granulated sugar, ½ teaspoon cinnamon and 1 tablespoon flour in a medium bowl; stir well to coat the apples. Spread the apples evenly over the pastry inside the border.

Combine oats, nuts, brown sugar and the remaining ¼ cup flour and ¼ teaspoon cinnamon in the medium bowl. Cut in butter until the mixture resembles coarse crumbs. Sprinkle the topping evenly over the apples. Bake until the pastry is browned and the apples are soft, 25 to 30 minutes.