Made these cupcakes twice and I can vouch for their yumminess, in particular, the peanut butter frosting. Do let the cupcakes set in the fridge for at least 15 minutes as the frosting is better cool (important if you live in the tropics). The ones in the picture above I made a few months ago. Looking at those cupcakes makes me want to make them again, now!
Here is the link to Ina's recipe (love her!) : http://www.foodnetwork.com/recipes/ina-garten/chocolate-cupcakes-and-peanut-butter-icing-recipe/index.html
I am contemplating next time I make them, I may try to use Nigella's moist chocolate cake recipe but keep to Ina's peanut butter frosting. Will post when I do (though I think it will be awhile before I have time to bake them).