you can't make a sweet cobbler out of a sour fruit

I know that isn't technically true, you can just add more sugar. But blackberry cobbler is a challenge because blackberries are so very large, and when you bite down on one, there is a burst of severe tartness. Even enrobed in lots of sugary juices, the tartness overwhelms and offputs.
This is a great cobbler dough and with whipped cream it was even a very nice dessert, but if I were to make it again, I would substitute another berry, elderberries, because they are smaller, blueberries, because they are a Superfood, gooseberries, because it would be so fun to say.