Preheat oven to 170°Celsius. Line baking trays with parchment paper.
Place butter in a medium-sized bowl. Add flour and mix on low speed until the mixture turns crumbly. If mixing by hand, rub in the flour and butter with your fingertips until both ingredients are well incorporated and the mixture turns crumbly.
Add the sugar and mix until it is well incorporated into the flour and butter.
Turn the mixture onto your workspace and press it together to form a ball.
Divide the dough into sections. Roll each section and cut it into rectangle bars.
Place the cut shortbread cookies onto prepared baking trays.
Bake for 10 minutes, until the sides of the shortbread start to turn light golden.
Remove the cookies from the oven and let them rest on the baking tray for a few minutes before transferring them onto wire racks to cool completely.
Store cookies in an airtight container.