Prep your tools and oven. Heat the oven to 400°F (200°C). Line a baking sheet with parchment paper. Zest the lemon first, then juice it and set both aside.

Mix dry ingredients. In a large bowl, whisk together flour, granulated sugar, baking powder, and salt. Keep it airy—this helps with a tender crumb.

Cut in the butter. Grate the cold butter on a box grater or cut it into small cubes. Toss it into the flour and use your fingertips or a pastry cutter to work it in until you have pea-sized pieces. Cold butter is key to flaky layers.

Combine wet ingredients. In a measuring cup, whisk the egg, heavy cream, vanilla, and lemon zest. If using buttermilk, whisk it in now. Stir in 1 tablespoon lemon juice.

Bring the dough together. Pour the wet mixture over the flour mixture. Use a fork or spatula to fold just until it starts to clump. Don’t overmix—it should look shaggy.

Add the blueberries. Gently fold in the blueberries. If using frozen, add them straight from the freezer to minimize streaking.

Shape the dough. Turn the dough onto a lightly floured surface. Pat it into a 7–8 inch circle, about 1 inch thick. If it’s sticky, dust your hands with flour and keep it quick to avoid warming the butter.

Slice and prep for baking. Cut the circle into 8 wedges. Transfer to the lined baking sheet, spacing them out. Brush tops with a little cream and sprinkle with turbinado sugar for crunch.

Chill briefly (optional but helpful). Pop the tray into the fridge or freezer for 10 minutes. Chilled scones rise higher and hold their shape.

Bake. Bake for 16–20 minutes, until the edges are golden and the centers are set. Rotate the pan once for even browning. Let cool on the sheet for 5 minutes, then move to a rack.

Glaze. Whisk powdered sugar with 1–2 tablespoons lemon juice until smooth and pourable. Drizzle over warm scones. Let it set for a few minutes before serving.