Preheat Oven: Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper.
Mix the Dry Ingredients:
In a large bowl, whisk together flour, sugar, baking powder, and salt.
Cut in the Butter:
Using a pastry cutter or fork, cut the cold butter into the flour mixture until it resembles coarse crumbs.
Add Milk and Blueberries:
Pour in the milk and gently stir until just combined. Carefully fold in the blueberries, being careful not to overmix.
Shape the Biscuits:
Turn the dough out onto a lightly floured surface. Gently pat it into a 1-inch thick round and cut into biscuit-sized rounds with a biscuit cutter or a glass.
Place the biscuits on the prepared baking sheet, about 1 inch apart.
Bake:
Bake for 12-15 minutes, or until the biscuits are golden brown on top.
Prepare the Glaze:
While the biscuits bake, whisk together the powdered sugar, milk, and vanilla extract until smooth.
Glaze the Biscuits:
Once the biscuits have cooled slightly, drizzle the glaze over the top.