If you use unsalted butter then add ¼ teaspoon of salt. Be sure to use a good quality butter, apparently this year 2022, store brand butter quality is not what it used to be. Less fat could mean a dry not so tasty cookie.
My Mom's Shortbread. Line 2 cookies sheets with parchment paper.
Beat butter until creamy about 3 minutes. Sift icing sugar, corn starch, salt and flour 4 times (I know, but it is worth it). Add the dry sifted ingredients to the creamed butter a little at a time and work in with a wooden spoon as long as possible*, then move to a lightly floured flat surface and knead until the dough cracks slightly.
Roll gently with a lightly floured rolling pin to 1/3" (1 cm) thickness or pat to desired thickness with the palm of your hand. Cut out with Christmas cutters and place on the prepared cookie sheets, bake for approximately 10-12 minutes, don't let them brown. Let cool on cookie sheets, then move to a wire rack.
My friend's Shortbread
Cream butter until fluffy, add sugar and cream together, then gradually add the flour and salt, mix with a wooden spoon* as much as you can. Move the mixture to a lightly floured flat surface and with your hands work the dough until it comes together and forms a ball.
Wrap the dough in plastic and refrigerate for approximately 60 minutes. On a lightly floured surface roll the dough to 1/3 inch (1 cm) thickness. Cut out into desired shapes, place on the prepared cookie sheets. Refrigerate the cookies while the oven is pre-heating. Bake for approximately 10-12 minutes. Let cool on cookie sheets and then move to a wire rack.
*or use the paddle attachment on the mixer until almost combined, then move to a lightly floured flat surface and continue with the recipe.
Notes
I have received a couple of messages saying my Mom's shortbread doesn't come together and they had to add butter, a lot of butter! So I just made it again and no extra butter is needed, but because flours absorb differently you may need to add a bit of butter, but start with 1 tablespoon, also please note this is a dough that needs to be kneaded not whipped and don't forget the sifting. It will be crumbly until you start to knead it, then with a little bit of elbow grease you will arrive at the desired dough. Or you can also bring it together with a stand up mixer. Hope this helps. Let me know. RosemaryStore the baked completely cooled cookies in an airtight container at room temperature for up to a week. I sometimes store mine in the fridge because I like cold cookies. They will last up to 10 days by storing them in the fridge.To freeze the shortbread cookies, place parchment paper in between the layers of the completely cooled cookies this prevents them from sticking together when they are in the containers for freezing, or you can also place the baked cooled cookies on a cookie sheet and freeze them, then move the frozen cookies to either airtight bags or containers. Baked Shortbread Cookies will last up to a month in the freezer.To thaw the cookies be sure to remove the frozen cookies from the bags or containers (this way no condensation will form) and let them thaw at room temperature. In our house no one waits for them to thaw!