Preheat oven to 375 degrees F (190 degrees C). Line baking sheets with parchment paper. Unwrap all the mini candy bars.
Empty the 2 cake mixes into a large bowl, and stir eggs, vegetable oil, and water into the mixes. The batter will be stiff. Roll heaping tablespoons of dough into 1-inch balls. Push a mini candy bar into the cookie ball, and carefully cover the entire candy piece with dough. If any chocolate is visible, the cookie will leak. Place the filled cookies onto the prepared baking sheets.
Bake in the preheated oven for 11 minutes. Cookies will not look brown on top. Cool for 5 minutes on the baking sheets before removing to finish cooling on racks.