Preheat oven to 350 degrees
Crust: (I used a whisk) mix whole wheat flour with brown sugar well, then cut butter into 1/2 inch pieces and mash into dough until it is in pea sized balls or smaller, and dough is crumbly
Sprinkle crust on a 13x9 inch pan evenly, then press down with a spatula
Before putting the crust in the oven, I grated my lemon to get 2 tsp of lemon zest just to make sure I wouldn't take too long when making the filling
Bake crust for about 20 minutes, or until golden.
Meanwhile.. In a medium bowl, mix egg and egg whites until fully blended, then add vanilla extract and 3/4 cup powdered sugar and mix well.
Then add lemon juice and the rest of your powered sugar (3/4 cup) and wait until sugar is completely dissolved before adding lemon zest.
Taste lemon filling and add powdered sugar to your liking (I usually add 2 tablespoons more)
As soon as crust is done, reduce the temp to 300 degrees and pour lemon mixture over hot crust. Place in oven for about 20-30 minutes, or until edges are golden and are starting to separate from pan
Let them cool for 10-15 minutes before taking them out of the pan! Makes 24 bars, 110 calories each.