In a mixing bowl, add butter, flour, powdered sugar until you have a crumbly dough.
Spread cookie dough in a square pan (Dimensions: 8x8), lined with parchment paper.
Chill in the fridge for 15 minutes.
Bake at 350 degrees F for 12-15 minutes or until it's golden brown on top.
Remove from oven and let it cool for 15 minutes.
While the shortbread cookie crust is cooling, prepare the lemon curd filling.
In a large mixing bowl, add lemon juice, zest, eggs, sugar, flour and mix until combined.
Pour this filling on top of the shortbread crust
Bake again at 350 degrees F for 25-30 minutes or until the top is almost set and the center jiggles slightly.
Remove from the oven and let it cool completely to room temperature.
Then cover with plastic foil and chill in fridge for 2 hours or overnight. Do not skip this step because it allows the filling to set further.
Remove from fridge and sprinkle powdered sugar on top.
Cut slices with a sharp knife and enjoy!