First, preheat your oven to 170℃ (325℉).

Then grease a 7*7 inch baking dish with softened butter/oil and line with parchment paper, set aside.

Now, to make the shortbread base, take 1/2 cup room-temperature butter, icing sugar, flour, and vanilla essence in a bowl.

Then combine everything using a spoon or simply just using your hand. Bring the mixture together with your hand until the dough forms a ball.

Now pat the shortbread dough into your lined prepared pan, ensuring it's nicely leveled and the sides are closed properly.

Then prick the crust all over with a fork so it doesn't rise up while baking.

Bake the shortbread crust in your 170℃ preheated oven for about 20 minutes or until it's slightly golden brown on the edges.

And prepare your lemon curd filling in the meantime while the crust is baking.

In another bowl, combine the eggs, sugar, flour, and lemon zest, then whisk together until well combined.

Then add the fresh lemon juice and mix again.

Take out the crust from the oven and pour the filling with the lemon filling you just prepared on the crust.

Bake again for 25 -30 minutes or until set. Once it's baked perfectly, there should be no jiggling on top, and a thin crackle crust will form on the top.

Allow it to completely cool to room temperature, then refrigerate for at least 2-3 hours or overnight before serving.

Cut it into 16 small squares (or you can cut it into 9 squares if you like bigger slices); dip your knife into hot water after each cut if you like to get a clean cut every time.

Dust with some icing sugar before serving and enjoy!