Step 1

Preheat oven to 375 degrees.

Step 2

In a medium bowl, whisk together the flour, sugar, baking powder, and salt. Cut in the butter into the flour mixture using a pastry cutter until the mixture is crumbly. Stir in the buttermilk until a dough ball forms. Set the dough mixture aside.

Step 3

In a large bowl, gently mix the berries, sugar, lemon juice, and cornstarch. Pour the mixture into a 9×13-inch baking dish. Drop the dough by rounded spoonfuls onto the berry mixture.

Step 4

Beat the egg and water together.  Using a pastry brush, lightly coat the dough with the egg wash. Sprinkle the dough with turbinado sugar and bake in a preheated oven for 45-50 minutes or until the cobbler dough is golden brown and the fruit is bubbling.