Herman the German Friendship Cake!

So, my lovely friend has brought me a German Friendship Cake called Herman. But, he's not actually a cake yet- I have to grow him and share him before I bake him!

I got a letter with him that reads-

Hi, my name is Herman and I am a sour dough cake, I'm supposed to be on the worktop, without a lid on, for 10 days, during which time you should feed me. If you put me in the fridge I will die and if I stop bubbling I am dead! Day 1 is the day you receive the mixture.
 
Day 1: When you get Herman please take off the lid and put the mixture in a large mixing bowl (2 litres+), cover the bowl loosely with a tea towel.
Day 2: Stir well
Day 3: Stir well
Day 4: Now I need feeding! Add the following ingredients, stir well and cover again: 1 cup plain flour, 1 cup milk, 1 cup sugar.
Day 5: Stir well
Day 6: Stir well
Day 7: Stir well
Day 8: Stir well
Day 9 : Hungry again! Add the same ingredients as day 4 and stir well.
 
Now divide the mixture into 4 equal portions.
Save 1 portion to make a cake for yourself tomorrow.
Give portion 2 and 3 away to 2 friends with a copy of these instructions.
 
Keep the final portion for your next cake and follow these instruction to grow me again.
 
Day 10: Make your Herman cake as follows:
Stir well and add the following ingredients:
1. 1 cup sugar
2. 2 cups plain flour
3. 2 eggs
4. 2 tsp cinnamon
5. 2 tsp vanilla essence
6. 2 tsp baking powder
7. 2/3 cup oil
8. 2 cooking apples peeled, cored and chopped into chunks
9. 1 cup raisins
10. optional extras like cherries nuts, chocolate chips, coconut
 
Mix all together and pour into a large roasting tin. Bake for 35 - 45 mins at 170 - 180 degrees. When cold cut into fingers.

I just hope I fair better than I do with plants- I seem to kill them very easily.

This is how Herman looked before I baked him! I added some blueberries to the mix- lovely!