I love the taste of the Dark Cocoa powder combined with the Dutch or Natural Unsweetened. It creates a richer color and flavor which I adore. But keep in mind, cocoa powder is quite dry. And Dark cocoa powder is even drier than Dutch or Natural Unsweetened. If you used only dark, the ice cream would be way too dry and bitter.  If you don’t have both cocoa powders on hand, just use the Dutch or Natural Unsweetened.