Preheat the oven to 400℉ and then grease a baking dish that is approximately 8" x 8" with 1 tablespoon of the butter. Set aside until needed.
In a large bowl, whisk together 4 ounces (½ cup) of the sugar, ¼ teaspoon of the salt, the cornstarch and 1 teaspoon of the fresh lemon zest.
When combined well, add in the berries and toss to coat evenly. Stir in the vanilla extract and the lemon juice.
Pour the berry mixture into the prepared baking dish, and then scrape any of the remaining juices from the bowl onto the fruit mixture.
In the same bowl used to mix the berries, add in the 2 tablespoons of the sugar, the remaining lemon zest, flour, baking powder, and the remaining ½ teaspoon of salt.
Using a pastry cutter or two butter knives, cut the remaining 3 tablespoons of butter into the flour until pea-sized lumps form. Then stir in the milk to form a soft dough.
Evenly cover the top of the berry mixture with spoonfuls of the dough mixture and then sprinkle the remaining ounce of sugar on top of the cobbler.
Place the baking dish into the preheated oven and bake until the cobbler is golden and bubbling, about 35 minutes.
To serve, use a large spoon to scoop out portions of the cobbler into individual dessert bowls. Serve warm, topped with the optional whipped cream or vanilla ice cream.