In a large bowl whisk the flour with the salt and cinnamon.
In the bowl of your electric mixer (or with a hand mixer), cream the butter until smooth (about 1 – 2 minutes). Add the sugar and beat until smooth and creamy (about 3 minutes). Beat in the zest and vanilla extract. Gently stir in the flour mixture just until incorporated. Fold in the chopped pistachios and dried cranberries. (Make sure that the nuts and cranberries are evenly distributed throughout the dough.).
Divide the dough in half. Place each half of dough on the center of a 14 inch (35 cm) length of parchment or wax paper (plastic wrap will work too). Smooth and shape the dough into an evenly shaped rectangle that is about 10 inches (25 cm) long and 2 inches (5 cm) wide. Then thoroughly wrap the shaped logs in the parchment or wax paper, twists the ends of the paper to seal the logs, and place in the refrigerator to chill for at least two hours, or up to three days. (The logs can also be frozen for about two months. If freezing, it is best to defrost the logs in the refrigerator overnight before slicing and baking.).
Preheat oven to 325 degrees F (160 degrees C) with the rack in the center of the oven. Line two baking sheets with parchment paper.
Using a thin bladed knife, slice the logs into ¼ to ½ inch (.5 to 1 cm) thick cookies. If dough is too hard to slice you may need to let the log set our for 5 minutes. Place the cookies on the prepared baking sheet, spacing about 2 inches (5 cm) apart.
Bake for about 15 – 18 minutes, or until the cookies are just beginning to brown around the edges. Remove from oven and cool on a wire rack. Check at 12 minutes - the type of pan you use can really make a big difference in cooking time.
Note. The original recipe calls for unsalted butter, I prefer my shortbread with salted butter, so try it either way.