Pre-heat the oven to 350 degrees and line 2 baking sheets with Silpat.
Put the softened butter and powdered sugar into your food processor and blend to cream them. You could alternatively use a hand-held blender.
Add the flour to the food processor, and blend to combine until the dough gathers. You could use a hand mixer for this part too.
Turn the dough out onto a flour dusted counter top to roll out. You could use more Namaste flour blend or even just some white rice flour which is super inexpensive. You can use a generous amount of rice flour or Namaste to dust the surface and your rolling pin. Roll the dough out to your desired thickness and cut out the shapes you want. Traditional shortbreads are about ¼ inch in thickness.
Place the cut cookies onto a Silpat lined baking sheet and bake at 350 degrees for 10-15 minutes, until the edges are just starting to become golden brown. The time will depend on how thick you made your cookies. The cookies in the images of this post take about 15 minutes. Cool for a couple minutes on the tray, and then transfer to a cooling rack to cool completely. If you want to dust your cookies with powdered sugar, it is best to do this while the cookies are warm so it sticks best.
Store your cooled cookies in an airtight container, or freeze them for long term storage.