Preheat your oven to 350℉ and line an 8x8 square baking pan with one piece of parchment paper. For best results, use a nonstick metal baking pan.
Mix all of the crust ingredients together until a thick dough forms.
Using your hands, press the dough into the baking pan and ensure to get the dough as flat and as even as possible. Also be sure to press the dough tight along the edges of the pan.
Bake the shortbread layer for 15-20 minutes. It should be golden brown when it’s ready.
When the shortbread has about 5 minutes of bake time remaining, whisk together the filling ingredients by hand. Be sure to whisk this really well so that the eggs are fully incorporated.
Once crust is golden, remove the pan from the oven and turn the temperature down to 325℉.
Then, give the lemon topping another good whisk and immediately yet slowly pour the filling onto the shortbread and place it back in the oven to bake. DO NOT wait for the shortbread to cool, this step should be done while the shortbread is hot.
Bake the lemon bars for 20-25 minutes. The lemon bars are ready when the center of the lemon topping moves just slightly, but isn’t super wet. I have found my oven’s sweet spot for this step is 22 minutes exactly.
Remove the lemon bars from the oven and allow them to cool completely at room temperature.
Once they are cool, place them in the fridge to finish setting for 3-4 hours minimum.
When you’re ready to serve, you can slice them to your desired size and add powdered sugar or whipped cream to the top if you’d like.