Dutch-Processed or Unsweetened Cocoa Powder?
I am following a recipe that calls for dusting cake with cocoa powder, but does not specify which type of cocoa powder. I have "regular" Hershey's Cocoa Powder, but read recently that Dutch-Processed cocoa powder should be used if you are not baking (e.g., in hot chocolate.) I don't understand completely the nuances of the two types. Any guidance?
Dutch-processed cocoa has been treat with an alkaline substance, resulting in a deeper chocolate flavor, a darker color, and little to no acidity in its flavor profile. Regular cocoa is reddish and is acidic. If you are just dusting a cake, either one will do. If it's being baked into a recipe, if the recipe does not ask for DPC, use regular. Oftentimes, the recipe will react regular cocoa with baking soda for leavening and if you sub in DPC, there's nothing for the soda to react with and the end result will turn out wonky.
As for drinking cocoa, either one is fine, keeping in mind that DPC will taste more chocolatey.
For dusting, use Dutch process. It's less acidic and much less bitter.
DPc can be subbed in for regular (American) cocoa powder in most recipes, but you also have to change the leavening. Rose covers this subject in depth in "The Cake Bible", and I think you can find the info on her website.