I tried making the Mini Chocolate Peanut Butter Whoopie Pies featured on Serious Eats. It called for dutch-process cocoa powder. All I could find at my grocery store that was dutch processed was Hershey Special Dark Dutch & Natural Cocoa. After I made these cookies/cakes, I tasted them and they tasted flat -- I can't find a better word to describe it other than flat; it tasted like the chocolate wasn't activated (if that makes sense). Was the cocoa I used the problem? Or is the cookie supposed to taste like this?