Preheat your oven to 350°F (175°C).
In a bowl, mix blackberries, 1/2 cup sugar, and lemon juice.
Pour the berry mixture into a greased baking dish.
In another bowl, combine flour, remaining sugar, baking powder, and salt.
Add milk, melted butter, and vanilla to the dry ingredients and stir until combined.
Pour the batter evenly over the blackberries.
Bake in the preheated oven for 45 minutes or until golden brown.
Let it cool for a few minutes before serving.
Serve warm, optionally topped with ice cream.
Enjoy your homemade blackberry cobbler!