In a large mixing bowl using a hand or stand mixer, combine butter, white sugar and brown sugar.
Add in vanilla and egg and mix until incorporated.
Slowly add in flour, corn starch, baking soda and salt and mix until a soft, thick dough forms.
Add in dried cranberries and white chocolate chips and stir until just combined.
Refrigerate for 1 hour or longer. (Don't skip this step!)
Preheat oven to 350 F and spray a baking sheet with non-stick cooking spray or use a non-stick silicone baking mat
Once dough is thoroughly chilled, roll or scoop into 2 inch balls and place about an inch or more apart on the cookie sheet
Bake for 10-11 minutes. *Cookies will appear undercooked when first removed from the oven. Do not cook any longer - the cookies will continue to set while left to cool on the cookie sheet.
Allow to cool at least 10 minutes before serving. Enjoy!