Each to their own.
Our local brewshop suggested we replicate it by doing the following.
1 x tin of Muntons Pale Ale
1 x small bag of stout grain (cant remember the size)
1kg of DME
600g of Dextrose (to bring the OG to 1.040)
20g Cascade hops (added to fermenter)
1 x 6 pack of white rabbit ('borrow' the yeast)
We only had a really small pot so had to steep the grain in a large bowl of boiled water.
The rest we put together the same as any normal extract beer.
We harvested the white rabbit yeast the week before and kept in a tupperware style container at 17 degrees. Feeding it some DME every second days and giving it a shake.
We bottled it on Sunday and it tasted amazing. Disclaimer: We do however think that White Rabbit Dark Ale is one of the best beers we have tasted to date.
I must say it is the tastiest beer (from racking unit) we have made so far of the 8 extract brews we have done. I am not sure if its the yeast or the small stout grain pack or the fact this is the first dark ale we have made?
All our other beers have had that good old home brew twang which we can't seem to shake no matter how much sanitising or Safale yeast we use or brewing at constant 17 degrees. But that whinge is for another thread.
Fingers crossed in 2 weeks this White Rabbit Dark will be tasting great.