Preheat oven to 350 Degrees. Line an 8 x 8 pan with parchment paper and set aside.
To prepare the crust:
In the bowl of a food processor, place flour, powdered sugar, salt and chilled Kerrygold butter. Pulse until mixture resembles a coarse meal and press into the bottom of the prepared pan. Bake for 30 minutes or until lightly browned.
To prepare the filling:
In a medium bowl, add the flour and sugar and stir to combine. Add the eggs, whisking to combine. Stir in the lemon juice and lemon zest.. Pour the filling over the shortbread crust and bake for 30 minutes or until set in center.
Allow to cool completely and then refrigerate for at least 2 hours. Dust the top with powdered sugar before cutting into squares and serving.