Preheat the oven to 350°F and line an 8 x 8 pan with parchment paper on all sides.

In a stand mixer with the paddle attachment, beat together the butter, sugar, flour and salt. The mixture will be crumbly.

Press the shortbread in an even layer into the prepared pan. I find using a rubber spatula to jab and smooth the dough to be effective. Use a fork to make a few holes in the crust. Bake the crust for 20 minutes.

While the crust bakes, make the lemon layer. Sift the sugar and flour together in a large bowl to prevent clumps.  Add the eggs, lemon juice and lemon zest, and whisk until completely combined. The mixture will be thin.

Take the crust out of the oven and pour the lemon layer over the baked shortbread crust.

Lower the oven temperature to 325°F and bake for 20-25 more minutes, or until the center no longer jiggles. Take the bars out of the oven and allow to cool completely.

Once the bars are completely cool, transfer to the fridge to set for 2 hours (or overnight) until ready to serve. Use a sifter to liberally dust the tops with powdered sugar. Slice and enjoy!