Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper or a silicone baking mat.

In a large mixing bowl, whisk together the flour, sugar, baking powder, and salt until well combined.

Add the cold, cubed butter to the flour mixture. Use a pastry cutter or two forks to cut the butter into the flour until the mixture resembles coarse crumbs with some pea-sized chunks of butter remaining.

Gently toss the blueberries into the flour mixture so they are lightly coated.

In a separate small bowl, whisk together the heavy cream, egg, and vanilla extract.

Pour the wet ingredients into the dry ingredients. Use a spatula to gently fold the mixture together just until a shaggy dough forms. Be careful not to overwork the dough or crush the berries.

Turn the dough out onto a lightly floured surface. Gently press it together and knead it 2 or 3 times just until it holds its shape.

Pat the dough into a disc about 7 inches wide and 1 inch thick.

Using a sharp knife or a bench scraper, cut the disc into 8 equal wedges.

Place the wedges onto the prepared baking sheet, leaving about 2 inches of space between each scone.

Brush the tops of the scones with the extra tablespoon of heavy cream and sprinkle with coarse sugar if desired.

Bake for 18 to 22 minutes, or until the tops and edges are lightly golden brown.

Let the scones cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.