Preheat oven to 350 degrees. Line a baking sheet with parchment paper or a non-stick baking mat.
In a large bowl, mix together the cake mix, eggs, oil, and vanilla until smooth.
Stir in ½ cup of the sprinkles.
Chill the cookie dough for about 30 minutes.
Roll the dough into 1-inch balls.
Pour the remaining ¼ cup sprinkles onto a small plate. Gently press each ball into the sprinkles, then place balls (sprinkle side up) about 2-inches apart onto the baking sheet.
Bake for 8-10 minutes, until the cookies are set and very lightly browned. (Be careful not to let the cookies get overly brown.)
Allow cookies to cool for a few minutes, before gently transferring to a wire rack to finish cooling.