Mix Dry Ingredients: In a large bowl, whisk together the flour, sugar, baking powder, and salt.

Grate Butter: Using a box grater, grate the frozen butter and add it to the dry ingredients. Toss to coat, then use a pastry cutter, fork, or your fingers to work it in until the mixture resembles coarse crumbs. Refrigerate the bowl while you prepare the wet ingredients.

Combine Wet Ingredients: In a separate bowl, whisk together the buttermilk or cream, egg, and vanilla extract.

Bring Dough Together: Pour the wet mixture over the flour mixture. Add the blueberries and gently stir until the dough begins to come together and looks moistened.

Shape the Dough: Transfer dough onto a lightly floured surface. With floured hands, shape it into a rough ball (it will be sticky). If needed, add a little more flour or cream. Press into an 8-inch (20cm) disc and slice into 8 wedges using a sharp knife or bench scraper.

Chill the Scones: Brush the tops with the heavy whipping cream and sprinkle with the granulated sugar. Place on a plate or lined baking sheet and refrigerate for 15–20 minutes while the oven preheats. Chilling helps prevent spreading and creates a flakier texture.

Bake: Preheat your oven to 400°F (204°C). Line a large baking sheet with parchment paper. Space the chilled scones 2–3 inches apart and bake for 22–25 minutes, or until the edges are golden and the tops are lightly browned.

Cool and Dust: Let the scones cool slightly, then dust some powdered sugar on top before serving and enjoy.