What's the real German cake recipe?

My best friend...love of my life loves black forest cake...he is German. According to him only his mom can make it best...but i want to give it a try. I've been looking at tons of recipes yet can't find one with rum on the list...he also says the cherries are soaked for so many hours. I am not rich in money and his birthday is April 10th. He says the cake is loaded with rum...Is anyone familiar with this recipe and if so where can I find this recipe...so I can start gathering my ingredients...also how long would you suggest the cherries be soaked...and can I use real cherries. Any help would be greatly appreciated.