Heat oven to 425°F. Line a baking sheet with parchment.
Whisk flour, sugar, baking powder, and salt in a large bowl.
Cut in cold butter until the mixture looks like coarse crumbs with a few pea-sized bits.
Stir in buttermilk, vanilla, and lemon zest until a shaggy dough forms. Do not overmix.
Gently fold in blueberries just until distributed.
Turn dough onto a lightly floured surface. Pat into a 1-inch-thick rectangle.
Fold dough like a letter, turn, and pat again. Repeat once to build flaky layers.
Cut into 8 squares or rounds and place on the prepared sheet, spacing slightly apart.
Brush tops with cream and sprinkle with turbinado sugar.
Bake until risen and golden, 15–18 minutes. Cool 5 minutes.
Whisk powdered sugar with lemon juice until smooth. Drizzle over warm biscuits and serve.