Shortbread is a lovely afternoon treat to enjoy along with a cup of tea or hot coffee. When dipped in chocolate and sprinkled with pistachios and sea salt, however, these shortbread cookies become something extra special and a hit at any cookie swap. Include them in a decorative tin, along with other favorite christmas cookies, and give as a food gift. Before starting this recipe, make sure your butter is softened; you want a smooth and creamy start to the cookie dough. If you dont like pistachios, consider using finely chopped pecans, walnuts, or peanuts. Use unsalted nuts, because you will be sprinkling the finished product with sea salt. For extra flavor, toast the nuts before sprinkling them on top of the shortbread. After shortbread has baked, let it cool slightly, about 5 minutes, before cutting it into triangles. Use a very sharp knife to get the cleanest cut, then let the shortbread cool completely.