Preheat your oven to 375°F (190°C) and generously grease a 9x13-inch baking dish with butter or non-stick cooking spray.
In a large mixing bowl, whisk together the 2 cups of flour, sugar, baking powder, baking soda, and salt.
In a separate medium bowl, whisk the buttermilk, eggs, melted butter, and vanilla extract until well combined and smooth.
Pour the wet mixture into the dry ingredients. Stir gently with a spatula until just combined. Be careful not to overmix; some lumps are completely normal.
Toss the fresh blueberries in 1 tablespoon of flour to prevent them from sinking, then gently fold them into the batter.
Spread the batter evenly into the prepared baking dish.
Bake for 25-30 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean.
Allow the dish to cool for 5 minutes before slicing. Serve warm with maple syrup.