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

In a large bowl, mix 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 the prepared baking sheet. Bake for 9 minutes—do not let the cookies get brown. Allow to cool on the 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.