How to make
The quantities of the products listed must be precise! Use a hand mixer. Baked in a preheated oven to 340°F (170 degrees). Bake on a baking sheet covered with parchment paper.
Cut the butter into cubes and beat it with a mixer for 1-2 minutes. Add the sugar and keep beating for about 4 minutes to achieve a white cream. Mix the flour, corn starch and salt in a bowl and add it gradually to the butter mix.
Mix on low speed, until all the ingredients are nicely incorporated to a ball of dough. Cover with cling film and refrigerate for about 30 minutes, or overnight.
Roll out the chilled dough into a sheet approximately 0.16″ (4 mm) thick and cut it into rectangles with a rectangular cookie form. If you don't have one, just cut the dough with a knife into 2″ (5 cm) long biscuits. Poke each biscuit with a toothppick, to help them cook evenly.
Refrigerate again before baking, allowing the butter to chill, so the biscuits keep their shape while baking, although they rise slightly. Make sure there is enough space between each biscuit.
Bake in a preheated oven to 340°F (170 degrees) for about 15 minutes. When they start turning golden brown around the edges, they are ready to be taken out of the oven. They should remain white in the center. The biscuits are very soft while still hot, but once they start cooling, they will harden.
PS: These are the shortbread cookies we used to buy in beautiful round tin boxes with Scottish paintings on them. Fantastic buttery taste, great for a Christmas gift and not only.