Preparation

• In a large bowl using a handheld mixer or stand mixer fitted with a paddle attachment, beat the butter for 1 minute on medium speed until completely smooth and creamy. Add the brown sugar and granulated sugar and mix on medium high speed until fluffy and light in color. Beat in the egg and vanilla on high speed. Scrape down the sides and bottom of the bowl as needed.
• In a separate bowl, whisk the flour, cornstarch, baking soda and salt together until combined. On low speed, slowly mix into the wet ingredients until combined. The cookie dough will be quite thick. Add the white chocolate chips, dried cranberries, and pistachios, mix on low for about 5-10 seconds until evenly disbursed. Cover dough tightly and chill in the refrigerator for at least 2 hours and up to 2 days.
• Remove cookie dough from the refrigerator and allow to sit at room temperature for 10 minutes (or 30 minutes if chilled longer than 2 hours). Preheat oven to 350°F (177°C) and line two large baking sheets with parchment paper or silicone baking mats.
• Once chilled, scoop and roll balls of dough, about 1 Tablespoon each, into balls. Bake for 8-10 minutes, until barely golden brown around the edges. Allow to cool for 5 minutes on the cookie sheet, then transfer to a cooling rack.