A buttery, melt in your mouth simple shortbread.
Preheat the oven to 170˚C.
Mix all the dry ingredients in a bowl.
Add the melted butter and stir until it is all combined.
Line a 28 x 18 cm lamington tin with baking paper and press the mixture in.
Bake at 170˚C for 30 minutes.
Remove from oven, cut into 24 squares, sprinkle evenly with caster sugar and prick each piece with a fork.
Return to the oven for 15 minutes.
Cool in the tin.
Don’t skip the final step of cutting and returning to oven.