✅ Preheat oven to 375°F (190°C).
✅ In a large bowl, combine blueberries, sugar, cornstarch, lemon juice, and vanilla. Toss to coat.
✅ Pour the blueberry mixture into a greased 9-inch baking dish.
✅ In a separate bowl, whisk together flour, sugar, baking powder, and salt.
✅ Add milk and melted butter to the dry ingredients and stir until just combined.
✅ Spoon the batter evenly over the blueberry mixture (it won’t cover it completely).
✅ Bake for 35–40 minutes, or until the topping is golden brown and the filling is bubbling.
✅ Let cool slightly before serving.