01 -
Preheat oven to 375°F (190°C). Line a 9x13" baking pan with parchment paper, leaving some overhang on the sides for easy removal.
02 -
In a food processor, combine flour, granulated sugar, baking powder, salt, cold cubed butter, egg, and vanilla. Pulse until the mixture resembles coarse crumbs. If you don't have a food processor, you can use a pastry cutter or two forks.
03 -
Press half of the crumb mixture firmly into the bottom of the prepared pan to form an even crust layer.
04 -
Bake the crust for 12 minutes until just beginning to set and very lightly golden. Remove from oven but keep the oven on.
05 -
While the crust bakes, in a large bowl, toss the diced apples with lemon juice, brown sugar, cinnamon, and cornstarch until evenly coated.
06 -
Spread the apple mixture evenly over the partially baked crust.
07 -
Crumble the remaining dough mixture evenly over the apple layer.
08 -
Bake for 30-35 minutes until the topping is golden brown and the apple filling is bubbling at the edges.
09 -
Allow the bars to cool completely in the pan before lifting out with the parchment paper and cutting into squares. For clean cuts, refrigerate for at least 2 hours before slicing.