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