All-Butter Scottish Shortbread

1. Gather the ingredients. 2. Preheat the oven to 325 F. Lightly grease a baking sheet. In a large bowl, cream together the butter, sugar, and salt until light, fluffy, and pale in color, either by hand or with the help of an electric mixer. This might take about 10 minutes. 3. In a separate medium bowl, whisk together the flour and cornstarch. Sift the dry ingredients into the bowl with the butter and sugar. Mix quickly and thoroughly to bring all the ingredients together but do not overmix. If worked too much, the dough will warm up and the shortbread will have a poor crumb. 4. Tip the mixture onto a cold and lightly floured work surface. Knead lightly and quickly to form a loose dough. 5. Roll out the dough between 2 sheets of parchment paper to 1/4 inch thick. Cut into desired shapes or rounds using cookie cutters. Place the shortbreads onto the prepared baking sheet, prick the surface all over with a fork, and bake for 25 minutes, or until pale brown and crisp. 6. Once they're cooked, sprinkle the warm shortbreads with superfine sugar and let cool completely on a wire rack.