Preheat oven to 350 degrees F. Spray a 9x13 pan with non-stick spray and set aside.
Scrub 2 lemons and pat dry. Zest both lemon rinds, then slice in half and juice lemon halves.
Combine all ingredients for the crust in a large bowl. Mix for about 5 minutes. Initially the mixture will resemble coarse crumbs, but if you continue to mix, it comes together and forms a ball. Press dough evenly into prepared pan and bake for 15 minutes, until golden brown.
While crust is baking, whisk together ingredients for the filling. Pour onto hot crust and return to the oven for 16-18 minutes, until mixture is lightly browned around the edges and is lightly set in the middle.
Stir the topping ingredients together and spread on top of lemon bars, covering the entire surface. Return to the oven for 10 minutes.
Stir together 1 TBSP lemon zest + 1 TBSP sugar and sprinkle on top of baked bars once they come out of the oven. Refrigerate for at least 6 hours, preferably 24 hours. Cut into squares & serve chilled. Store leftovers in the fridge in an airtight container.