Preheat your oven to 350°F and line a large baking sheets with parchment paper.
In a large bowl, beat the butter, brown sugar, and granulated sugar together on medium speed until combined, about 2 minutes. Beat in the egg and vanilla.
In a separate bowl, whisk together the flour, baking soda and salt together.
Over low speed, slowly mix the wet ingredients into the dry ingredients.
The cookie dough will be soft and thick.
Add the white chocolate chips and cranberries, beat over low speed until combined.
Cover dough tightly and chill in the refrigerator for at least 1 hour.
Preheat the oven to 350°F and scoop the dough into balls.
Arrange dough balls 3 inches apart on the prepared baking sheets.
Bake for 10-12 minutes or until lightly browned around the edges. The centers will still look soft.
Allow the cookies to cool on the baking sheet for 5 minutes before digging in.