Preheat the oven to 350 degrees and line a 9x13” pan with parchment paper.
Cream together butter, cream cheese, and sugar.
Mix in eggs, egg white, lemon juice, and vanilla.
Slowly stir in flour, baking powder, baking soda, and salt.
Fold in lemon zest.
Pour batter into the prepared pan, spread evenly, and bake for 22-25 minutes (batter will be thick) - if needed add an additional two minutes until a toothpick comes out clean from the center.
Let cool for 30 minutes and then remove the cookie bar from the pan using the parchment paper and let cool completely on a cooling rack (30 minutes to 1 hour).
Make the glaze and cut the cookie bars before drizzling the glaze over the bars. Let cool and dust with powdered sugar.