Preheat your oven to 375°F (190°C).
In a large bowl, combine the blueberries, granulated and brown sugar, flour, lemon juice, and zest. Gently stir in the melted butter and set aside.
4 cups blueberries, ¼ cup sugar, ¼ cup brown sugar, 2 teaspoons flour, 1 tablespoon lemon juice, 1 teaspoon lemon zest, 4 tablespoons butter
In a separate bowl, whisk together flour, both sugars, baking powder, and salt. Add milk and vanilla extract, and stir just until smooth (don’t overmix).
1 cup flour, ½ cup brown sugar, ½ cup granulated sugar, 2 teaspoons baking powder, ¼ teaspoon salt, 1 cup milk, 1 teaspoon vanilla
Pour the blueberry mixture into a greased 9x13-inch baking dish. Gently pour the batter over the top—do not stir. Sprinkle lightly with cinnamon for a warm finish.
Cinnamon
Bake for 25–30 minutes, or until the top is golden and a toothpick inserted into the batter comes out clean.
Best enjoyed fresh from the oven with a scoop of vanilla ice cream or a dollop of whipped cream.