Some chocolate cakes are brown and others are an intense dark brown on the verge of black. I'm looking for a cocoa powder or technique that will produce the intense dark brown result. I live in NYC.
I think you're looking for Dutch-processed cocoa. Cakes made with it tend to come out darker than those made with regular cocoa powder.
I use valhrona is very very dark and produces a cake that is almost black. Its available at many stores I'm sure but I get it at whole foods columbus circle.
I've made plenty of chocolate cakes with Hershey's Special Dark cocoa powder (dutch processed) and they come out dark and chocolatey. Easily available. I think the chocolatey-est cakes are made with cocoa powder by the way.
You want a cocoa powder that is a good 24% fat. You can usually find one in a good store's bulk foods section. The grocery store varieties tend to be about half that.
I like Dutch-processed cocoa for its dark colour, and King Arthur Flour also sells black cocoa, for really dark results.
I use Hershey's Special Dark or Droste's cocoa. Have never had a problem with my cakes coming out too light.
There is a product called Black Cocoa Powder -- used to be available at King Arthur's, not sure if it still is. It is very bitter, you only use it as part of your cocoa. It adds a lot of darkness to the look and mystery to the taste. Also, for regular cocoa powder but a dark look, search for Black Magic Cake recipe; been around for decades. It is a wonderful, flavorful, moist chocolate cake (the one I make 90% of the time) with coffee and buttermilk as the liquids. It's very dark, but doesn't hold up to stacking very well.