How To Make blackberry cobbler:

Step 1: Ready the oven and preheat to 175 degrees C or 350 degrees F.
Step 2: Apply cooking spray in a 9×13-inch baking dish.
Step 3: In a small mixing bowl, add in the 1/2 cup of sugar and cornstarch. Whisk until well mixed.
Step 4: In another mixing bowl, add in the blackberries and drizzle 1/4 cup of melted butter on top.
Step 5: Sprinkle the cornstarch mixture on top and toss to coat the blackberries completely.
Step 6: Arrange the coated berries into the greased baking dish.
Step 7: In a small mixing bowl, add in 1 1/2 cup of sugar, flour, baking powder, and salt. Whisk until well mixed.
Step 8: Add in the milk, 1/4 cup of melted butter, and vanilla extract. Stir until well combined and a little lump.