Preheat oven to 375°F; grease an 8x8-inch dish or 6 ramekins.
Gently toss blueberries, 2/3 cup sugar, cornstarch, lemon zest, and juice in a medium bowl; transfer to dish.
Whisk flour, 1/3 cup sugar, baking powder, and salt in a large bowl.
Stir melted butter, milk, and vanilla into dry ingredients just until combined and smooth.
Pour batter evenly over berries; gently spread to cover. Sprinkle with raw sugar.
Bake 30-35 minutes until topping is golden and set and berries bubble. Cool 10 minutes; serve warm.