Perk up our Basic Shortbread Wedges with this espresso flavored variation.
Butter an 8 1/2-inch cake or springform pan; set aside. Sift together flour and salt into a small bowl; set aside. Place butter in bowl of electric mixer fitted with paddle attachment. Cream until fluffy, 3 to 5 minutes. Add sugar, and continue to beat until very light in color and fluffy, occasionally scraping down the sides of the bowl with a spatula, about 2 minutes more. Add vanilla, if using. Dissolve 2 tablespoons espresso powder in 1 teaspoon hot water. Add mixture to creamed butter-and-sugar mixture with vanilla, before adding flour. Add flour mixture, and combine on low speed, scraping with spatula if necessary, until flour is just incorporated and dough sticks together when squeezed with fingers.
Pat dough into prepared pan. If rolling out dough to cut into shapes, form into a flat disk; wrap in plastic. Chill until firm, at least 1 hour.
Roll dough out 1/4 inch thick. Cut into ovals with 2-inch cutter. Score a line down the middle with the back of a knife; chill.
Heat oven to 325 degrees. Bake until firm, about 20 minutes.