In a small bowl, whisk together flour, cake mix, cocoa powder, and baking soda.
In a large bowl using a handheld mixer, beat butter, brown sugar, and white sugar until creamy. Add egg and vanilla extract and mix until fluffy.
Add in dry ingredients and mix until combined. Lastly, fold in the white chocolate chip with a spatula.
Refrigerate dough for 1 hour. After 1 hour is up, roll dough into balls (use about 1 tbsp of dough per cookie) and place on prepared pans, putting 12 cookies per pan.
Preheat the oven to 350°F.
Put cookie dough balls in the freezer for about 10 minutes while the oven preheats.
Bake cookies for 12-14 minutes. You will see the tops cracking when they are done.
Top with extra white chocolate chips as soon as they come out of the oven.