After reading some of the comments on the double chocolate cake - I noticed that some stated they had used Dutch process cocoa in the recipe. This led me to a google search on how to substitute Dutch process cocoa for natural cocoa in a recipe. Here is what I found:
According to "The King Arthur Flour Baker's Companion":
"If a recipe calls for natural cocoa and baking soda and you want to use Dutch-process cocoa, substitute an equal amount of Dutch-process cocoa but replace the soda with twice the amount of baking powder. If the recipe calls for Dutch-process cocoa powder and baking powder, substitute the same amount of natural cocoa but replace the baking powder with half the amount of baking soda."
If you are interested in reading the original article, it can be found here:
I haven't tried this myself so I can't say for sure, but I plan on making the double chocolate layer cake next week using my Valrhona, so I'll let you know how it goes!