10tablespoonsunsalted butter, frozen and grated, plus 2 tablespoons, melted, for brushing
Instructions
Preheat oven to 425°F and line a baking sheet with parchment paper or silpat.
Place the blackberries in the freezer until ready to use. Whisk together the milk and sour cream and place keep chilled in the refrigerator.
In a large bowl, whisk together the flour, sugar, baking powder, baking soda, zest and salt. Add the grated butter and milk mixture and stir with a wooden spoon or rubber spatula. Turn the dough over onto a well-floured counter top and bring the dough together with clean, well-floured hands. Work quickly so not to warm the dough and sprinkle on flour as necessary if the dough becomes too sticky.
Roll out the dough into a 12x12-inch square. Fold the square into thirds, like a business letter. Then, fold into thirds width-wise to form a 4x4-inch square. Place on a floured plate and place in the freezer for 5 minutes.
Generously flour the counter top and roll out the dough into a 12x12-inch square. Evenly sprinkle on the chilled blackberries and gently press them down into the dough. Roll the dough into a tight log and place seam-side down. Use a rolling pin to roll and flatten the dough into a 12x4-inch rectangle. Cut out 8 triangles using a knife or bench scraper.
Transfer to the prepared baking sheet, spacing 1-inch apart. Brush with melted butter and sprinkle on sugar. Bake for 18 to 20 minutes, rotating the pan half way. The scones are done when the outer edges are golden brown. Carefully transfer to a wire rack and let cool for 10 minutes to serve warm. Or, let cool completely to serve at room temperature.