Preheat oven to 350 degrees F and spray a 9 x 13 cake pan with cooking spray.

Using a mixer, mix together the butter, brown sugar, and white sugar. Until the sugar is dissolved. The mixture will have turned a lighter color. Add eggs, vanilla, cinnamon, salt & baking powder, mix well.

Add flour a cup at a time and mix. The batter will be thick. Remove from the mixer and add the apples and walnuts (if desired) and mix by hand.

Spread mixture evenly into the prepared pan. Sprinkle the top with the 1/2 cup of granulated sugar and the 1 Tbl. of ground cinnamon.

Bake for 50 minutes or until knife comes out clean. Remove from the oven and cool slightly before eating.

Once cooled, cut into bars and enjoy!