01 - Preheat oven to 375°F. Lightly grease a 9x9-inch baking dish with butter or cooking spray.
02 - In a large bowl, combine frozen blueberries, granulated sugar, cornstarch, lemon juice, ground cinnamon, and salt. Toss until berries are evenly coated. Spread mixture in the prepared baking dish.
03 - In a separate bowl, whisk together all-purpose flour, granulated sugar, baking powder, baking soda, and salt until well combined.
04 - Pour melted butter, whole milk, and vanilla extract into the flour mixture. Stir gently until just combined—the batter will be thick and slightly lumpy. Avoid overmixing.
05 - Drop spoonfuls of batter evenly over the blueberry filling, covering most of the surface. Leave small gaps for steam to escape and fruit to bubble through during baking.
06 - Bake for 40 to 45 minutes until the topping is golden brown and set, and the berry filling is bubbling around the edges.
07 - Let the cobbler rest for at least 15 minutes before serving. Serve warm with vanilla ice cream or whipped cream.