Start by preheating your oven to 180°C (350°F). This helps the cobbler bake evenly. A hot oven ensures the top becomes golden. While the oven heats, prepare your baking dish and ingredients.

Place butter in your baking dish and let it melt in the oven. Watch carefully so it does not burn. Melted butter gives rich flavor and helps create a crispy crust.

In a bowl, mix flour, sugar, baking powder, and salt. Add milk and vanilla extract slowly. Stir gently until smooth. Do not overmix. The batter should be slightly thick but pourable.

Take the baking dish with melted butter out of the oven. Pour the batter over the butter. Do not stir. Let it sit as it is. This step creates layers while baking.

Spread blackberries evenly over the batter. Sprinkle a little extra sugar on top if you like sweetness. The berries will sink slightly while baking and create a juicy layer.

Place the dish in the oven and bake for 40–45 minutes. The top should turn golden brown. The edges will look crisp. Insert a knife to check if the center is cooked.

Remove from the oven and let it cool for 10 minutes. This helps the cobbler set. Serve warm for the best taste. It pairs well with ice cream or whipped cream.