Preheat oven to 350 degrees F and line a 8x8 baking dish with parchment paper leaving some paper hanging over the edge (or you can just grease the pan)

In a bowl, cream together butter and sugar until light and fluffy

Add in the discard and salt and mix well

Add in flour and mix until combined

Press dough into a parchment lined baking dish and bake for 20-25 minutes until the edges are lightly golden

In a medium bowl, mix sugar and flour. Add in the eggs, lemons, and lemon zest and mix until combined

Pour the mixture over the crust. Bake an additional 20-25 minutes until the filling is set and no longer jiggles in the middle

Let the bars cool completely. Once they are cooled, use the parchment paper overhand to lift the bars out of the baking dish

Dust with powdered sugar and cut into desired size squares