Blueberry and Peach Cobbler

I realize that cobbler recipes are a dime a dozen; I have made many different recipes and find there is some little issue each time: watery filling, stodgy biscuits, dull flavor etc. This time I wed two recipes- the filling from Joanne Chang's book Pastry Love and a really good cobbler biscuit recipe from the NYT Cooking section.  I thought I should note it here for my own sake so that I'm not fishing out two different recipes (and trying to remember which two were the best combo) each time I make cobbler.
For the filling:
1000 g (8 cups) blueberries
1 1/2 lbs (680 g) peaches, sliced unpeeled
3/4 cup sugar
4 T cornstarch
zest from 1 lemon
In a medium saucepan, combine half the blueberries, all the peaches, sugar, zest and cornstarch. Cook over medium heat for about 5 minutes until the juice released is nice and purple and looks like a thickened pie filling. Add the remaining blueberries and put it into a 13 x 9 ceramic baking dish.
Preheat oven to 350º.
For the biscuits:
1 1/2 cups flour
1/4 t kosher salt
1 1/2 T sugar
2 1/4 t baking powder
6 T unsalted butter, cubed
3/4 cup heavy cream
In a mixing bowl whisk together all dry ingredients; add butter cubes and with the paddle attachment mix until it resembles coarse sand. Add the cream and toss with a fork until it just comes together- don't overwork it. Using your hands, make patties with the dough and arrange over the blueberries. Bake for 50-60 minutes. Serve with additional whipped cream.