i think it would need a nice malty backbone...maybe some maris otter with munich or vienna malt and a high mash temp...nice, subtle roasted/coffee flavors (but not too powerful, maybe small amounts of roasted barley and british chocolate) and some hoppiness to balance it all out. Ahtanum and cascade sound good to me...if that's what they use (i've never tried Ahtanum)
hopefully some more experienced recipe forgers will chime in, cuz i would love to brew something in this style that works!
EDIT: I think i'll also have to find another bottle to know what i'm looking for!
