I ALWAYS, and I mean ALWAYS, have a box of yellow cake mix, a box of vanilla pudding, and some chocolate syrup in my house on reserve just in case I need to make this cake.
Ingredients:
1 box yellow cake mix
1 small package Instant vanilla pudding
4 eggs
3/4 cup oil
1 cup water
1/2 cup Hershey's chocolate syrup
1 cup chocolate chips
Directions -- Mix the cake mix, pudding mix, eggs, oil, and water until smooth. Grease bundt cake pan and pour 3/4 of the batter into pan. Add chocolate syrup and chocolate chips to the remaining batter and stir to combine; pour into pan (on top of the "vanilla" batter) and swirl lightly with a knife. Bake at 350 degrees for 60-65 minutes.
Once cooled, remove cake from pan and drizzle with chocolate frosting (I just warm up chocolate frosting from the can...yes, it is cheating, but it is great!).