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

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

Cut the cold butter into the dry ingredients using a pastry cutter or fingertips until the mixture resembles coarse crumbs.

Stir in the milk and vanilla extract just until combined. Do not overmix.

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

Turn the dough out onto a lightly floured surface and gently pat into a 1-inch thick rectangle.

Cut into rounds using a biscuit cutter and place on the prepared baking sheet.

Brush the tops lightly with melted butter.

Bake for 15–18 minutes, or until the biscuits are puffed and golden brown.