01 - Preheat oven to 400°F. Line a baking sheet with parchment paper.
02 - In a large bowl, whisk together flour, sugar, baking powder, and salt until well blended.
03 - Add cold, cubed butter to the flour mixture. Cut in butter using a pastry blender or fingertips until mixture resembles coarse crumbs with some pea-sized pieces remaining.
04 - In a separate bowl, whisk together milk, egg, and vanilla extract until fully combined.
05 - Pour wet ingredients into the dry mixture. Gently stir with a spatula or wooden spoon until just barely combined—some dry streaks should remain.
06 - Gently fold in blueberries, taking care not to overmix or crush them. Stop as soon as berries are evenly distributed.
07 - Turn dough onto a lightly floured surface. Gently pat into a 1-inch thick rectangle, handling as little as possible to maintain texture.
08 - Use a 2.5-inch round cutter to cut biscuits. Press straight down without twisting. Regroup scraps and pat to 1-inch thickness to cut remaining biscuits.
09 - Place biscuits on the prepared baking sheet, spacing them 2 inches apart. Sprinkle tops with coarse sugar if using.
10 - Bake for 18 to 20 minutes until tops are golden brown and biscuits have risen. Rotate pan halfway through for even baking.
11 - Let cool on the baking sheet for 5 minutes before transferring. Serve warm with butter, honey, or lemon glaze.