Add the butter to a large bowl and blend it until smooth using an electric mixer set at medium speed for about 30 seconds.
Add the icing sugar and continue mixing until well incorporated. Scrape down the sides of the bowl and combine thoroughly.
Add flour and mix at low speed until well blended. The mixture will be crumbled and soft.
Pat dough into an ungreased cookie sheet, lined with parchment paper, with the parchment paper hanging off the sides to make it easy to lift out the cookies. Alternatively you can roll out the dough so that it's about 1/4 of an inch in thickness, you can knead it a bit just so that the dough comes together, but don't overwork it, then cut into your desired shape. Pierce the shortbread with a fork.
Bake for 12 to 15 minutes, or until just done (slightly golden in color). Do not let them get brown. Remove from the oven. If using a cookie sheet, lift out the cookies from the sheet using the parchment paper and cut into desired shapes. Finish cooling the cookies on a cooling rack.
Because I'm using salted butter there's no need to add salt to the recipe, if you only have unsalted butter, add about 1/4 tsp salt to the recipe.
For the video I divided the dough in half and used one half in an 8x8 inch baking pan lined with parchment paper, and rolled the rest to use with the cookie cutter.
This recipe will yield about 36 cookies.
Bake your cookies on the middle rack of your oven and only one cookie sheet at a time, for even baking.
Traditionally shortbread cookies are very pale in color, you don't want them golden brown. In order to do this, we have to use a low oven temperature, which is why we bake these cookies at 325°F.
Piercing the shortbread with a fork is not only for decoration, but it's meant for more even baking. Poking holes in the shortbread allows the heat to penetrate the cookie, hence more even baking.
Notice I'm using powdered sugar here. You'll see lots of shortbread recipes using granulated sugar. Because I'm using powdered sugar, there's no need to cream the butter and sugar for a long time, plus it gives us extra buttery, melt-in-your mouth cookies. If you only have granulated sugar, you can still use it, just make sure you mix it with the butter for as long as 10 minutes, until creamy and smooth.
To freeze, place shortbread cookies in an airtight container and place in the freezer for up to 3 months.