Combine 2 c flour, 1/2 c sugar, baking powder, and salt in a large bowl
Cut in butter until crumbs are the size of small peas
Stir in egg yolks
Divide mixture in half, press one half over the bottom of a 13x9x2 inch baking dish
Combine apples, 3/4 c. sugar, 1/4 c. flour, and cinnamon, spread over bottom crust.
Crumble remaining crust over the top and brush egg white over.
Bake at 350 degrees for 40 minutes.
Cool and cut into bars. Drizzle with thin powdered sugar glaze if desired, or serve warm with ice cream.
