Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking dish or a 10–12 inch cast iron skillet with butter or non-stick spray.
In a large bowl, combine the blackberries, 1/2–3/4 cup granulated sugar (to taste), lemon juice, lemon zest (if using), cornstarch, 1/2 teaspoon vanilla extract, and a pinch of salt. Gently toss until the berries are evenly coated and look glossy and slightly syrupy. Let the mixture sit for 5–10 minutes while you prepare the batter.
5 cups blackberries, 1/2–3/4 cup granulated sugar, 1 tablespoon lemon juice, 1 teaspoon lemon zest, 2 tablespoons cornstarch, 1/2 teaspoon vanilla extract, salt
In a small saucepan or microwave-safe bowl, melt the 8 tablespoons (1 stick) of unsalted butter. Set aside to cool slightly; it should be warm but not piping hot when added to the pan.
8 tablespoons unsalted butter
In a medium bowl, whisk together the flour, 1 cup granulated sugar, baking powder, and 1/4 teaspoon fine sea salt.
1 cup all-purpose flour, 1 cup granulated sugar, 2 teaspoons baking powder, 1/4 teaspoon fine sea salt
In a separate bowl or large measuring cup, whisk together the milk, 1 teaspoon vanilla extract, and ground cinnamon (if using).
3/4 cup whole milk, 1 teaspoon vanilla extract, 1/2 teaspoon ground cinnamon
Pour the wet mixture into the bowl with the dry ingredients and stir gently until just combined. The batter should be smooth and pourable, similar to pancake batter. Do not overmix; a few small lumps are fine.
1 cup all-purpose flour, 1 cup granulated sugar, 2 teaspoons baking powder, 1/4 teaspoon fine sea salt, 3/4 cup whole milk, 1 teaspoon vanilla extract, 1/2 teaspoon ground cinnamon
Pour the melted butter into the prepared baking dish or skillet and tilt the pan to coat the bottom evenly with butter.
8 tablespoons unsalted butter
Pour the cobbler batter evenly over the melted butter in the baking dish. Do not stir. Spoon the blackberry mixture evenly over the batter, including any juices in the bowl, and again do not stir.
5 cups blackberries, 1/2–3/4 cup granulated sugar, 1 tablespoon lemon juice, 1 teaspoon lemon zest, 2 tablespoons cornstarch, 1/2 teaspoon vanilla extract, salt, 1 cup all-purpose flour, 1 cup granulated sugar, 2 teaspoons baking powder, 1/4 teaspoon fine sea salt, 3/4 cup whole milk, 1 teaspoon vanilla extract, 1/2 teaspoon ground cinnamon, 8 tablespoons unsalted butter
Bake at 350°F (175°C) for 40–50 minutes, or until the topping is deep golden brown around the edges, the blackberry filling is bubbling in the center, and a toothpick inserted into the bready part of the topping comes out without wet batter (berry juice is fine). If the top is browning too quickly, tent loosely with foil for the last 10 minutes of baking.
Let the cobbler cool for 15–20 minutes to allow the filling to thicken. Serve warm with vanilla ice cream, whipped cream, or a drizzle of heavy cream, if desired.
vanilla ice cream, lightly sweetened whipped cream, heavy cream