2 cups all-purpose flour
1/4 cup and 2 tablespoons sugar
1 1/2 teaspoons baking powder
1/2 teaspoon baking soda
1/4 teaspoon salt
1 stick (1/2 cup) cold unsalted butter, cut in bits
3/4 cup buttermilk
1 cup sugar
1 teaspoon grated lemon zest
2 Tablespoons of both lemon juice and water, mixed
2 pints each of fresh blueberries & blackberries (8 cups total)
1 teaspoon vanilla extract
2 Tablespoons cornstarch, mixed with:
3 Tablespoons water
Place oven rack in lower third of oven. Heat to 450°F. You’ll need a 13 x 9-in. baking dish or a shallow 3-qt baking dish.
Dough: Whisk flour, 1/4 cup sugar, the baking powder, baking soda and salt in medium bowl until blended. Cut in butter with a pastry blender until coarse crumbs form. Refrigerate flour mixture and buttermilk separately until ready to top cobbler.
Filling: Mix sugar, zest and lemon juice mixture in a large deep skillet over high heat. Stir in 1 pint blueberries and cook, stirring, about 10 minutes until hot and bubbly. Stir in cornstarch mixture, bring to a boil and boil 1 minute or until thickened. Stir in remaining blueberries, blackberries and the vanilla. Spread in baking dish.
Stir flour mixture and buttermilk with a fork until a biscuit-like dough forms. Drop eight 1/4-cupfuls, evenly spaced, over hot filling. Sprinkle biscuits with remaining 2 Tbsp sugar.
Bake 15 to 20 minutes or until biscuits are golden and filling is bubbly. Cool in dish on a wire rack. Serve warm or at room temperature.