Preheat oven to 350°F (177°C). Line large baking sheet with parchment paper or silicone baking mat. Set aside.

In a large bowl, mix together the cake mix and baking powder. Set aside. In a smaller bowl, whisk together the eggs, oil, and vanilla by hand. Add the egg mixture to the cake mixture and stir to form a dough. Stir vigorously until all of the pockets of dry cake mix are gone. Gently mix in the sprinkles—you do not want to dye the cookie dough by over stirring the sprinkles.

Drop rounded 1-inch balls of dough onto prepared baking sheet. Bake for 9 minutes—do not let the cookies get brown. Allow to cool on baking sheet for 3 minutes; they will be very soft at first. As they cool, the tops will settle down so you will not have to press the cookies down yourself. Transfer to a wire rack to cool completely. Store in an airtight container, for up to one week.