In the bowl of a stand mixer fitted with the paddle attachment, blend together the butter, powdered sugar, and orange zest on medium speed until the mixture is pale and fluffy, approximately 3 minutes. In a separate bowl, sift together the flour and cornstarch. Reduce the mixer speed to low and gradually incorporate the dry mixture into the butter mixture until fully combined. Gently fold in the chopped cranberries and pistachios until evenly distributed throughout the dough. Divide the dough into two portions and shape each into a compact log roughly 2 inches (5 cm) in diameter. Wrap each log tightly in plastic wrap and refrigerate for a minimum of 1 hour, or up to 2 days. Logs may also be frozen for up to 8 weeks at this stage. When ready to bake, preheat the oven to 300°F (150°C) using the convection setting and line two baking sheets with parchment paper. Slice the chilled dough into rounds approximately ¼ inch (6 mm) thick and place them 2 inches (5 cm) apart on the prepared baking sheets. Bake for 15 to 17 minutes until the edges are a light golden color while the tops remain pale. Allow cookies to cool completely before transferring to an airtight container. Store for up to 1 week.