In a large bowl, combine the cake mix, eggs, oil, chocolate chips and about 3/4 of the M&Ms. Stir to combine (it may be a little stiff).
If you have time, place the cookie dough in the fridge to chill for 15 minutes.
Pre-heat the oven to 350℉/180℃. Line two large baking sheets.
Scoop large tablespoon size balls of dough onto the baking sheets, a few inches apart. Top with a sprinkle of white chocolate chips and a few of the M&Ms.
Bake 15-20 minutes, until the edges look crisp. Let cool before serving!