Mix together by hand flour, sugar and butter until crumbly.
Press firmly into 8 x 8 pan.
Bake at 350º x 15 minutes till brown.
While base is baking ~
In medium size bowl, whisk together second amount of sugar, flour, eggs, lemon zest and lemon juice.
Pour over crust after removing from oven.
Then bake another 25-30 minutes until set ( set = when you jiggle the pan, the liquid is semi-firm)