Place all the dry ingredients, with the cold butter cut into chunks, into the food processor. After a few pulses, the butter is mixed in.
Next, add the ice water a little at a time; a few more pulses and it is ready to roll (literally)! Don't add too much water right away, you can always add more, but you can't take it out. Your pastry will sort of come together, but still be somewhat crumbly when ready (see pics in body of recipe.) Too much water will make the crust tough.
Shape the shortbread pie pastry into a ball on the counter, but do not knead. Cover with cling wrap and refrigerate for at least 20 minutes. If I'm in a hurry I skip this without any trouble.
Finally, press the dough onto a flour dusted countertop and roll out the pie crust pastry to the desired size. If making a top and bottom crust, use ⅔ for the bottom, and ⅓ for the top.
Use as desired for savory dishes or sweet.
Makes enough for one, double homemade pie crust (bottom and top). Another way to use the pastry is to make tartlets. This recipe will make about 24 tartlet shells.