Preheat your oven to 350°F (175°C).
Line your baking pan with parchment paper.
Leave some overhang on the sides.
This helps lift bars out easily later.
Mix flour, sugar, and salt together.
Cut cold butter into small pieces.
Add butter to the flour mixture slowly.
Mix until it looks like coarse crumbs.
Press this mixture into your prepared pan.
Make sure it's even across the bottom.
Bake for 20 minutes until lightly golden.
Crack eggs into a large bowl.
Add sugar and mix them well together.
Zest your lemons carefully over the bowl.
Squeeze fresh lemon juice and add it.
Whisk in the flour until completely smooth.
The mixture should be bright yellow.
Pour lemon filling over the hot crust.
Return pan to the oven immediately.
Bake for 30-35 minutes until the filling sets.
The center should jiggle slightly when done.
Don't overbake or they'll be dry.
Let the bars cool completely in pan.
This takes about 2 hours at room temperature.
You can refrigerate them to speed this up.
Once cool, lift using the parchment paper.
Cut into squares using a sharp knife.
Dust generously with powdered sugar before serving.