01 - Preheat oven to 375°F. Lightly grease a 9x9-inch baking dish with cooking spray or butter.
02 - In a large bowl, combine frozen blueberries, granulated sugar, cornstarch, lemon juice, ground cinnamon, and pinch of salt. Toss until berries are evenly coated. Spread mixture in prepared baking dish.
03 - In a separate bowl, whisk together flour, sugar, baking powder, baking soda, and salt until well combined.
04 - Pour melted butter, milk, and vanilla extract into flour mixture. Stir until just combined; batter will be thick. Do not overmix.
05 - Drop spoonfuls of batter evenly over blueberry filling, covering most of surface while leaving small gaps for fruit to bubble through during baking.
06 - Bake for 40 to 45 minutes until topping is golden brown and cooked through, and berry filling is bubbling around edges.
07 - Let cobbler cool for at least 15 minutes before serving. Serve warm with vanilla ice cream or whipped cream if desired.