Secret ingredient: Rice flour is what makes this shortbread extra tender, crisp and light!
Preheat oven to 300*. Place the butter and sugar in the bowl of a mixer. Using the paddle, cream the butter and sugar on high until light and creamy.
Add the flour to the mixing bowl. On low speed, mix together until it becomes a smooth dough. Stop mixing when all the flour is fully incorporated. Do not over mix.
Prepare a 15cm round cake tin with parchment on the bottom. Add the dough into the pan and lightly pat it down. Emphasis on lightly.
With the dough still in the cake tin, using a clean knife, cut the disk into 10 wedges (like a pizza). Sprinkle with some of the demerara sugar. Place in the oven and cook for 45-60 minutes or until the edges become very lightly browned.
Remove and allow to cool completely, at least 1 hour. Flip the cake tin over onto a wire rack to remove the shortbread in one piece. Allow to continue to cool completely. Break apart and store in an airtight container.