Preheat oven to 350 degrees.

To make the crust: Whisk together the flour, sugar, baking powder and salt. Cut in butter using pastry cutter, or your fingers, work the butter into the flour until it becomes a coarse meal. Stir in the egg yolks until the dough becomes smooth.

Divide the dough in half and press half into the bottom of a 13 x 9 x 2 – inch pan to form a thin crust.

To make the filling: Toss the sliced apples with the sugar, flour, cinnamon, and lemon juice. Spread the apple slices evenly over the crust.

Break off small pieces of the remaining dough and flatten them with your fingers by pressing them into the palm of one hand. They will be about the size of fifty cent pieces or just smaller than the palm of your hand, but do not have to be uniform.

As you make these discs, lay them over the apples to make an uneven top crust.

Brush the top crust with a beaten egg white.

Bake for about 45 minutes until the top is light golden brown and the apples are bubbling slightly.

Cool the bar cookies in the pan and cut them into bars.