Adapted from Tartine's recipe for currant scones. UPDATE 5/12/2023: I recently updated my method, which is highlighted in bold in the recipe below. If you prefer the old method, see the notes below the recipe. In sum I now:  Grate the butter using a box grater.  Use 1/4 cup more blueberries. Use the same tea towel method I use for my pie dough to bring the dough together. Cut the dough into 6 large triangles as opposed to smaller circles.  As always, for best results, use a digital scale to measure.  To freeze: After you place the scones on a sheet pan, transfer them to the freezer. Freeze until solid; then transfer the scones to an airtight container or bag. When you are ready to bake, there's no need to thaw them. Bake as directed below straight from the freezer. The scones shouldn't take much longer to bake from frozen, but keep an eye on them at the 20-minute mark.  To make your own buttermilk: Place 1 tablespoon of vinegar or lemon juice in a liquid measuring cup. Fill cup with milk (2% or whole is best) until it reaches the 1-cup line. Let stand for five minutes. Use as directed.