Preheat your oven to 350 °F
Making sure that there are no lumps in your brown sugar ( this can lead to lumps in the cookies that don't melt) cream together your butter and brown sugar completely.
Add in the icing sugar and combine until smooth.
Add in the flour slowly, with the mixer on low - this is not whipped shortbread after all- until the dough is completely mixed together.
Roll the dough until it's a 1/4 inch thick and cut into shapes as desired. Pierce the top of each with a fork two or three times.
If you have unsalted butter, simply add in 1/2 tsp of salt into the flour, then mix in as directed.
Nutritional values will vary depending on the size of the cookies you bake.