HOW TO MAKE IT :
- For the scones: Preheat the oven to 425˚. Line a baking sheet with parchment paper. Grate the frozen butter on the large holes of a box grater into a bowl. Return to the freezer until ready to use.
- Whisk the cake flour, all-purpose flour, granulated sugar, baking powder, salt and baking soda in the bowl of a stand mixer. Combine the heavy cream and crème fraîche in a small bowl and chill.
- Add the frozen butter to the flour mixture. Using the paddle attachment, mix on medium-low speed until the butter is worked in, about 1 minute. Add the cream mixture and mix briefly, just until large clumps form, about 30 seconds. (The dough should hold together when you squeeze it.)
- Turn out the dough onto a floured piece of parchment paper. Pat and press into a rough square, then use a rolling pin to roll it into a 12-inch square. Using the parchment to help you, fold down the top one-third of the square, then fold the bottom third up over it, like a letter. Flip over the dough, re-flouring the parchment, and roll out again into a 12-inch square.
- Scatter the blueberries on top of the dough, pressing them in. Roll up the dough into a log, like a jelly roll, using the parchment to help you (it’s OK if the berries poke through). Turn the log seam-side down and flatten so it is about 4 inches wide and 1 inch thick. Using a sharp knife, cut the log into three 4-inch squares, then cut each square diagonally in half.
- Transfer the scones to the baking sheet and brush with heavy cream. Bake, rotating the pan once, until the scones are golden brown, about 20 minutes. Let cool completely on the baking sheet.
- For the icing: Whisk the powdered sugar, 2 tablespoons plus 2 teaspoons milk, the vanilla bean paste, melted butter and salt until smooth. Stir in 1 more teaspoon milk if the icing is too thick. Spread on the scones and sprinkle with the pearl sugar.
