Preheat oven to 375 degrees F.
Toss nectarines and blueberries with the granulated sugar, ginger, salt, vanilla extract, lemon juice, maple syrup, and cornstarch. Place the fruit in a 2-quart buttered baking dish or eight 4-ounce ramekins. Bake in the middle of the oven for 10 minutes. Remove and allow to cool slightly.
Make the biscuits while the nectarines are baking. Begin by stirring together in a bowl, flour, sugar, baking powder, baking soda, salt, and cardamom. With your fingers pinch in the butter until the mixture resembles small peas. Quickly stir in the buttermilk to form soft dough. Knead into a ball. Roll the dough out on a well-floured surface to 1/2-inch thickness. Using a 1-inch biscuit cutter, cut out 16 biscuits. Re-roll the trimmings and cut an additional 8 biscuits.
Sprinkle the candied ginger over the cooled nectarines. Arrange the biscuits on top of the fruit, fitting snuggly next to each other. Brush with buttermilk and sprinkle the turbinado sugar.
Reduce oven temperature to 350 degrees F and bake the cobbler 20 to 25 minutes or until the biscuits are golden brown. Serve with ice cream or soft whipped cream.