Mary Ann, take a regular Devil's Food or Fudge cake mix and add about a cup of sour cream.
Found this recipe that the poster uses for every box cake mix she bakes.
(Use regular cake mix, not one that already has pudding in it. Or, if the mix has pudding, omit the additional pudding mix listed below.)
1 box cake mix
1 box (4 serving size) pudding mix (either same flavor as cake or complimentary flavor)
4 whole eggs
1/2 c. water
1/2 c. oil
1 c. sour cream
