Blackberry Peach Cobbler
- 2 tablespoons cornstarch
- 1 1/2 cups plus 1 teaspoon sugar
- 1 1/4 lb blackberries (5 cups)
- 2 lb peaches (6 medium), peeled, pitted, and cut into 1/2-inch-thick wedges
- 3 cups all-purpose flour
- 1 tablespoon baking powder
- 1 teaspoon salt
- 2 sticks (1 cup) cold unsalted butter, cut into 1/2-inch cubes
- 1 cup plus 3 tablespoons whole milk
Put oven rack in middle position and preheat oven to 425°F. Butter a 13- by 9- by 2-inch glass or ceramic baking dish (3-quart capacity).
Whisk together cornstarch and 1 1/2 cups sugar in a large bowl, then add blackberries and peaches and toss to combine well. Transfer to baking dish and bake until just bubbling, 10 to 15 minutes.
While fruit bakes, whisk together flour, baking powder, and salt in another large bowl, then blend in butter with your fingertips or a pastry blender until mixture resembles coarse meal. Add milk and stir just until a dough forms.
Drop dough onto hot fruit mixture in 12 mounds (about 1/3 cup each), then sprinkle dough with remaining teaspoon sugar. Bake cobbler until top is golden, 25 to 35 minutes. Serve warm.
Cobbler can be baked 6 hours ahead and cooled completely, uncovered, then chilled, covered. Before serving, let stand at room temperature 1 hour, then reheat in a preheated 350°F oven until warm, about 20 minutes.