Whisk together the flour, baking powder, baking soda, and salt and set aside.
Beat butter and sugars until light and creamy. Add the egg and vanilla and mix just until blended. Reduce mixer speed to low and add the flour mixture.
Stir in white chocolate chips and cranberries until they are distributed evenly.
Cover dough and chill for at least one hour or overnight.
Use a 2-tablespoon cookie dough scoop and scoop out dough onto a parchment or silicone-lined cookie sheet about 2 inches apart.
Bake for about 10 minutes or until edges are lightly browned. Cool the cookies on the baking sheet for about 10 minutes, then transfer to a rack to cool completely.