Lightly butter a 13x9” pan and line with parchment paper. (Use two sheets, one going the long way, the other across the middle. The parchment should cover the bottom of the pan and extend up all four sides.)

1. Prepare the crust: Combine the flour, powdered sugar and cold butter cubes in a food processor. Pulse on and off, scraping the sides in between, until the mixture resembles coarse cornmeal.
   
   
2. Gently press the crust mixture evenly into prepared pan.
   
   
3. Refrigerate the crust for 30 minutes while you preheat the oven to 350 degrees.
   
   
4. Bake for 20–25 minutes, or until light golden brown.
   
   
5. Meanwhile, prepare the filling: Whisk the dry ingredients together. Add the eggs and combine well.
   
   
6. Whisk in the lemon juice, zest and milk.
   
   
7. Pour the filling mixture on top of the warm crust.
   
   
8. Bake for 20 minutes or until the filling is firm to the touch.
   
   
9. Transfer the pan to a wire rack and cool for 30 minutes.
   
   
10. Lift the paper from pan and place the bars on a cutting surface.
    
    
11. Sprinkle with powdered sugar and the zest and cut into diamonds. (see How To: Lemon Diamonds in Catherine Christensen's Cookie Bars
    column. )