Buttermilk Sugar FOR THE DOUGH, PLACE FLOUR in a bowl and rub in butter until fine and mealy. Do not allow to become pasty. Stir in 1 cup of the buttermilk, adding the remainder if necessary. Press dough together on a floured surface, wrap in plastic wrap and allow to rest while preparing filling. Preheat the oven to 450F and set a rack in the middle level. Place the peaches in a bowl and add the remaining filling ingredients, except the butter. Toss well to combine and pour filling into a 2-quart gratin dish or other baking dish. Distribute pieces of the butter evenly on the filling. On a floured surface, with the palms of the hands, press out the dough to the size of the baking dish and slide a thin cookie sheet under it. Slide the dough onto the filling. Cut 3 or 4 vent holes in the crust with the point of a knife. Paint the top crust evenly with the buttermilk and sprinkle with sugar. Bake the cobbler about 20 minutes, until crust is well-colored and filling is bubbling. Cool slightly on a rack and serve warm or at room temperature.