How to Make It
Preheat the oven to 450°. Combine the nectarines, blackberries, and lemon juice in a bowl. Mix the sugar and 2 tablespoons of the flour and toss with the fruit.
In a medium bowl, mix the remaining 1 cup of flour with the baking powder and salt. Cut in the butter until the pieces are the size of small peas. Stir in the milk. Gather the dough into a ball and transfer to a lightly floured surface. Roll the dough into an 8-inch square about 1/4 inch thick.
Pour the fruit and its juices into an 8-inch square glass baking dish. Lay the dough on top of the fruit. Place a sheet of foil in the bottom of the oven to catch any drips. Bake the cobbler for 20 minutes, then reduce the heat to 300° and bake for about 5 minutes longer, or until the crust is golden and the fruit is bubbling around the sides. Serve warm with a scoop of ice cream, if desired.