Ghirardelli Double Chocolate Shortbread Cookies
*If you don't have a stand mixer and prefer to use a hand mixer, use room-temperature butter, bake the full 18 minutes, and leave on baking sheets to cool.
Make-Ahead Instructions: Dough logs will keep in the refrigerator for up to 4 days and in the freezer for up to 1 month. If refrigerated, let dough logs stand at room temperature for about 10 minutes to soften slightly before slicing. If frozen, let dough logs stand at room temperature for about 30 minutes.
For the chocolate, you can also use 1 (10-ounce) package Ghirardelli bittersweet chocolate chips.