Add vanilla and flour then mix until dough comes together.
Shape dough into a 6 inch disk, cover in plastic wrap and refrigerate for 20 minutes.
Roll out the dough to about ⅓ inch thickness. It is easier if you roll out the dough on lightly floured parchment paper.
Use a cookie cutter to cut out your cookies. My cookie cutter is about 1 inch by 2 ½ inches and my baking time is perfect for that. If you don't have a cookie cutter, you can use a sharp knife to cut cookies. If your cookies are smaller, you need a little less baking time. Larger, a little more time.
Bake 10 minutes, watching closely. Shortbread cookies don't look very different when they are baked. When they just start browning on the bottom, they are done and should be removed from the oven.
Let cool for a couple of minutes on the baking sheet then remove and put onto a wire rack to cool.
Place in an airtight container. These are fine in the refrigerator for about a week. To freeze, either individually freeze on ungreased cookie sheets and, when frozen, place in a plastic bag. Or, these can be frozen in an airtight container with parchment paper between the layers. Make sure cookies are thoroughly cooled before freezing.
Nutrition (I am not a nutritionist. These are estimates only)