Whisk flour, sugar, baking powder, cinnamon, and salt together in a large bowl. Grate the frozen butter using a box grater. Add it to the flour mixture and combine with a pastry cutter, 2 forks, or your fingers until the mixture comes together in pea-sized crumbs. See video for a closer look at the texture. Place in the refrigerator or freezer as you mix the wet ingredients together.

Whisk 1/2 cup heavy cream, the egg, and vanilla extract together in a small bowl. Drizzle over the flour mixture, add the blueberries, then mix together until everything appears moistened.

Pour onto the counter and, with floured hands, work the dough into a ball as best you can. Dough will be sticky. If it’s too sticky, add a little more flour. If it seems too dry, add 1–2 more Tablespoons heavy cream. Press into an 8-inch disc and, with a sharp knife or bench scraper, cut into 8 wedges.

Brush scones with remaining heavy cream and, for extra crunch, sprinkle with coarse sugar. (You can do this before or after refrigerating in the next step.)

Place scones on a plate or lined baking sheet (if your fridge has space!) and refrigerate for at least 15 minutes.

Meanwhile, preheat oven to 400°F (204°C).

Line a large baking sheet with parchment paper or silicone baking mat. After refrigerating, arrange scones 2–3 inches apart on the prepared baking sheet.

Bake for 22–25 minutes or until golden brown around the edges and lightly browned on top. Remove from the oven and cool for a few minutes before topping with vanilla icing.

Leftover iced or un-iced scones keep well at room temperature for up to 2 days or in the refrigerator for up to 5 days.