Preheat oven to 400°F.

In a medium bowl, toss the diced apples with the lemon juice and sugar until well coated.

Grease a baking pan with the butter and spread apples evenly on pan.

Bake at 400°F for 15 minutes. Set aside to cool.

Once cool, mix the apples with the cinnamon and applesauce until smooth.

Using a countertop mixer, cream together the sugar and butter until smooth (~2-3 minutes on medium speed).

Add egg, vanilla, and cinnamon; mix until smooth.

Add both flours and mix until a smooth dough forms.

Preheat oven to 350°F. Line 2 baking trays with parchment paper; set aside.

Divide dough into two pieces of equal size. Working with one piece at a time, place dough on a well-floured countertop. Roll into a long rectangle about 4” x 20”. (Note: Essentially roll this dough as thin as possible before it begins to tear.)

Use a spoon to spread half of the apple mixture in a 1” line down the center of the dough.

Fold both sides over the filling and then pinch dough seam together.

Slice into bars and transfer onto parchment-lined baking sheet.

Repeat process with remaining piece of dough.

Bake at 350°F for 12-14 minutes, or until tops of bars are crispy and light golden brown.

{Optional} Sprinkle tops of bars with cinnamon-sugar mixture.

Let cool slightly, but serve warm. (For leftovers, reheat in oven or toaster oven until tops turn crispy again.)