Preheat oven to 350 degrees. Line a baking sheet with parchment paper.
In a large mixing bowl, add butter, and sugar. Beat until light and fluffy. About 2 minutes. The batter will become a light color.
Add in the egg and vanilla and beat until incorporated.
In a separate bowl, sift in the corn starch, baking soda, baking powder, and flour. No one wants a lump of corn starch in their cookie!
Add all of the flour mixture into the butter mixture and mix on low. This will help avoid a flour shower. When the flour is almost completely combined, bump up the speed to medium for about 30 seconds.
Mix in the white chocolate chips and cranberries with a spatula.
Using a large cookie scoop, scoop the cookies onto the cookie sheet. Bake for 14 minutes or until done. Remove from the oven and let cool for 5 minutes before transferring to a cooling rack.