Preheat the oven to 350˚F.
Lightly grease a 9x13 baking dish with a bit of butter.
Wash the berries, then arrange the berries in the baking dish; sprinkle with flour, sugar, and salt, and mix to combine.
Dot with the chopped butter and bake for 18 to 22 minutes, or until bubbly around the edges. Remove from oven and stir.
In the meantime, whisk together the ingredients for the topping; flour, sugar, baking powder, and salt.
Melt the butter and then whisk in the vanilla extract.
Pour the melted butter mixture over the flour mixture and stir until everything is well combined and the batter is crumbly.
Using your hands, sprinkle the batter over the berries.
Bake for 20 to 25 more minutes, or until the top is golden brown.
Remove from oven and let stand 10 to 15 minutes.
Serve warm with ice cream.