Preheat your oven to 425°F (220°C). Line a baking sheet with parchment paper.

In a large mixing bowl, whisk together the flour, baking powder, salt, and granulated sugar.

Add the cold, cubed butter to the flour mixture. Using a pastry cutter or your fingers, work the butter into the flour until the mixture resembles coarse crumbs.

Gently fold in the fresh blueberries, being careful not to crush them.

In a separate bowl, combine the buttermilk and vanilla extract. Pour the buttermilk mixture into the flour and blueberry mixture. Stir until just combined; do not overmix.

Turn the dough out onto a lightly floured surface. Pat it into a rectangle about 1-inch thick. Cut out biscuits using a round cutter or a glass. Place the biscuits on the prepared baking sheet.

Brush the tops of the biscuits with milk and sprinkle with additional sugar.

Bake for 12-15 minutes or until golden brown. Remove from the oven and let cool slightly before serving.