Made these Classic Shortbread Cookies for the Club last night. Martha Stewart does have some good recipes. She beat out Cook's Illustrated Shortbread.
Makes 8 wedges
2 cups all purpose flour
1 1/4 teaspoons coarse salt
1 cup (2 sticks) unsalted butter at room temperature, plus more for the pan
3/4 cup confectioners' sugar
Sift flour and salt into a bowl; set aside. Put butter into the bowl of an electric mixer fitted with the paddle attachment. Mix on medium-high speed until light and fluffy - 3 to 5 minutes. Gradually add sugar; beat until pale and fluffy, about 2 minutes. Reduce speed to low. Add flour to mixture all at once; mix until just combined.
Preheat oven to 300 degrees, with rack in upper third of oven.
Using plastic wrap, press dough into a buttered 10-inch fluted tart pan with a removable bottom. With plastic on dough, refrigerate 20 minutes. Remove plastic wrap. Cut out a round from center using a 2 1/4-inch cookie cutter; discard (or eat...honestly, Martha, sometimes I wonder). Put cutter back in center. Cut dough into eight wedges with a paring knife. Using a wooden skewer (a fork messes up the dough and makes it crumble), prick all over at 1/4-inch intervals.
Bake until golden brown and firm in center, about 1 hour. Transfer pan to a wire rack. Recut shortbread into wedges; let cool completely in pan. Cookies can be stored in an airtight container at room temperature up to 2 weeks.
Here is a good link: