This is the moistest, easiest bundt cake that I've found. I make it often, usually making it a poppy seed cake (my hubby's favorite) but have also used mini chocolate chips.
One side note: don't use the poppy seeds if you foresee having a drug test in the near future, as it will make your test come out a positive for opiates. Seriously, it will; because the poppy seed is obviously in the family of opiates, but with no "high". This cake will make you giddy though!
Poppy Seed Cake
*1 yellow cake mix, dry
*1 cup water
*1/2 cup oil
*2 TBS lemon or orange juice
*1 small pkg. vanilla instant pudding
*1/4 cup poppy seeds, or mini choc chips
*4 TBS of white and chocolate frosting for drizzle
Combine all ingredients well. Bake in well greased bundt pan. Cool for 10 minutes. Invert pan onto plate. To drizzle with frosting; I use left-over frostings in my refrigerator from other cooking projects, however, if you don't happen to have that at the time, you may certainly use the "canned" frostings. I put a small amount of frosting in a ziploc bag, then microwave it for approximately 10-15 seconds, softening the frosting slightly to the melted point. Clip a very small hole in the corner of the bag and drizzle over the top of cake, using one flavor, then the other.
This cake gets moister as it sits, so it's best if you wait for the next day to dive in, but don't feel obligated to do so!