Preheat oven to 350 degrees Fahrenheit.
Lightly spray 13x9 baking dish with cooking spray and set aside.
Clean blueberries and add to a large bowl. Then add lemon juice and zest to bowl, stir to combine.
In a small bowl, whisk together ½ cup sugar, 1 tablespoon flour and cinnamon then sprinkle over berries and toss to coat.
Transfer blueberry filling to prepared baking dish.
In a medium bowl, whisk together flour, 1 cup sugar, baking powder and salt.
Cut butter into pieces, then add it to bowl with dry batter mixture. Blend, or cut it, into flour mixture until small crumbles form.
Gradually add milk and stir after each addition until well combined.
Spoon topping onto blueberries and spread slightly, mixture will be thick but will spread while baking.
Bake for 40-45 minutes at 350 degrees Fahrenheit in preheated oven or until golden brown on top.
Remove from oven and let cool 10-15 minutes. Serve with vanilla ice cream if you like
Store leftovers in refrigerator.