How to spice up boxed cake mix

We had a birthday party today.  Last year I made a chocolate hazelnut torte from scratch.  It was awesome!  This year they wanted yellow cake with chocolate frosting and sprinkles.  I asked if it was ok to make it from a box or from scratch.  Box it was.  We looked around and decided to alter the box instructions to make it extra tasty.

Add one more egg

Replace the water with milk

Replace the vegetable oil with melted butter or ghee