Preheat oven to 475?F. Line a large baking sheet with a Silpat baking mat or parchment paper. Set aside.

In a large bowl, whisk together the flour, sugar, baking powder, baking soda, salt, and lemon zest. Set aside.

In a medium bowl, combine cold buttermilk and the slightly cooled melted butter. Stir with a spatula until combined and small clumps form. Stir in the vanilla.

Add buttermilk mixture to dry ingredients and stir until just combined and the biscuit batter pulls away from the sides of the bowl. Gently fold in the blueberries.

Scoop biscuit batter (approximately 3-tablespoons per biscuit) and drop on prepared baking sheet, spacing biscuits at least 2 inches apart. Sprinkle the tops with turbinado sugar.

Place the baking sheet in the oven, and bake until the biscuit tops are golden brown, about 10 to 14 minutes.

Remove from the oven and let biscuits cool for 5 minutes on the baking sheet. Transfer biscuits to wire rack and let cool completely.

While the biscuits are cooling, make the lemon glaze by whisking together the confectioner?s sugar, lemon juice, and zest until smooth. Drizzle the glaze over the cooled biscuits. Serve.