Scottish Shortbread

I like Scottish shortbread for its rich buttery flavor but I don't recall ever baking some on my own.  So today I decided to give this a go.
I added in some Earl Grey but since I have no chance to infuse the tea in this recipe, the taste didn't come out much.
But this is so good together with a cup of tea over some reading up.
Source: Two Tarts
What you need:
145g unsalted butter, softened
40g icing sugar
20g sugar
210g plain flour
Method:
Preheat the oven 180°C.  Lined a 8” X 8” baking pan.
Beat butter, icing sugar, castor sugar and salt until it is light and fluffy. (medium speed)
Sift in plain flour, mixed to combine.
Lightly knead until well blended and smooth. If the dough is too dry to hold together, sprinkle a few drops of water over it, just enough to for dough to come together.  Do not over add water.
Firmly press the dough into the pan to form a smooth, even layer. Pierce the dough deeply with a fork all over in a decorative pattern.
Bake until it has a slight tinged of pale gold and just slightly darker at the edges, 40-50 minutes.
Remove the pan to a rack and let cool until barely warm.
Cut almost through the dough to form bars.
Let stand until completely cool.
Retrace the cuts, and separate into bars.

Air fryer: 160°C for 30 mins. with foil cover for 20 min and the last 10 mins uncovered.

Enjoy!