Bear in mind that is just my opinion, but here is what I would do. I would use a base of mostly pale extract with a light hop schedule. I would steep about 1/2 lb of crystal 40 L and a handfull each of chocolate malt and roasted barley. For spices you are going to have to go by your own taste, but I would add a stick of cinnamon, a teaspoon of allspice, 3 whole cloves and a teaspoon of nutmeg in the final 5 minutes of the boil. Taste after fermentation has died down and adjusting the spicing then. You could also toss in the zest from a tangerine and/or a lemon.
WWCD: What Would Chthulu Do?