The cake I'm eating this week is the second stab at a recipe attributed to Green & Black's but like the first there's a dense layer at the bottom. I'm beginning to suspect the recipe was meant for a two layer cake instead of one but I'm done experimenting. For now.
Nigella Lawson's recipe, on the other hand, seems foolproof. I used Green & Black's Dutched cocoa but I think the next time I'll use Lindt & Sprügli's Ghiradelli or Hershey's Scharffen Berger for a darker, less reddish color and some additional bitterness.