The story of Herman

About two weeks ago, my son returned from his girlfriend's with a bowl of a strange cream coloured mixture.
"I've brought you Herman" he said.  And with a brief "Oh, you'll need these instructions too" he was off.
Turns out that Herman is a German Friendship Cake mixture.  A basic sourdough base to which you add flour, sugar and milk a couple of times over the course of 10 days and keep loosely covered at all times on your work surface.  Herman grows to quite a size and bubbles away to prove he is still alive.  The initial Herman mix must have yeast included in it!  Then you divide Herman into four.  Pass three portions onto friends and add more ingredients to the remaining one and bake it.
Here's Herman's progress:

The final ingredients I added included cooking apples, cinnamon and sultanas and before it went into the oven, a generous sprinkling of brown sugar and melted butter to give it a crisp crunchy topping.
And the verdict?  Let's just say that I baked Herman on Monday night, it is now Wednesday morning and there is just one slim portion left.  Husband is now very upset that he can never have Herman again, unless someone passes a portion of him back to me in 10 days time!