Preheat the oven to 450ºF. Line a baking sheet with parchment paper.
In a large bowl, whisk together the all-purpose flour, baking powder, granulated sugar, and kosher salt. Stir in the frozen shredded butter to evenly coat it with the flour, breaking up any large clumps.
2 cups All-purpose flour, 1 tbsp Baking powder, 1 tbsp Granulated sugar, 3/4 tsp Kosher salt, 1/2 cup Unsalted butter
Pour in the cold buttermilk and stir just until a shaggy dough forms. Gently fold in the blueberries, being careful not to crush them.
1 cup Buttermilk, 1 cup Fresh blueberries
Turn the dough onto a lightly floured surface. Pat it into a rectangle about 1 inch thick. Fold the dough over itself several times to create flaky layers, then gently pat it back into a rectangle. Cut the biscuits using a 2-inch biscuit cutter. Place them touching on the prepared baking sheet. Place the baking sheet in the freezer for 10-15 minutes.
Bake for 13 to 15 minutes, or until the tops are lightly golden and the biscuits have risen beautifully.
Let them cool for at least 5 minutes. Whisk together the powdered sugar, vanilla, and kosher salt, then add enough milk to make a smooth glaze. Drizzle it over the warm biscuits before serving.
1/2 cup Powdered sugar, 1/4 tsp Vanilla extract, 1 pinch Kosher salt, 1-2 tbsp Milk