Preheat the oven to 325 degrees. Line your baking sheets with parchment or a baking mat. z.In a large mixing bowl, cream the room temperature butter with your mixer for about 2-3 minutes until the butter is a very pale yellow. Add in the icing sugar and beat for another minute.
This is key in creating melt-in-your-mouth shortbread.
Next add in the flour and cornstarch and beat until combined. Alternatively, you can knead the dough with your hands until the dough cracks.
Turn out onto a lightly floured surface, roll to ½" thick and cut out using your favorite cutters.
Now chill your cookies for about 20 min in the freezer. Don't skip this step!
Bake for 20-30 minutes until just baked through and barely golden on the bottom. Allow to cool on the baking sheet before moving them.