Preheat oven to 375°F. Line a rimmed baking sheet with parchment paper.
Into a large bowl, sift together flour, sugar, and baking powder. Using fingers, rub butter into flour mixture until it resembles fine bread crumbs. Stir in cranberries. Create a well in the centre of flour mixture.
In a medium bowl, whisk together buttermilk, ¼ cup water, and 2 eggs until well combined. Add to well in flour mixture and gently mix together with a fork or hands until a dough forms.
Turn dough out onto a lightly floured surface, and knead gently until smooth by patting dough and folding it in half 4 to 5 times. Using a rolling pin, roll out dough to a ¾-inch thickness. Using a 2¼-inch round cutter dipped in flour, cut as many scones as possible from dough without twisting cutter, rerolling scraps once. Place scones, evenly spaced, on prepared baking sheet.
In a small bowl, whisk remaining egg until no streaks remain. Brush tops of scones with egg.
Bake scones until golden brown and puffed, 12 to 15 minutes. Serve warm or at room temperature.
Notes
*If caster sugar is not available, extra-fine sugar can be used.
RECOMMENDED CONDIMENTS Clotted cream Black currant conserve
Recipe by TeaTime Magazine at https://teatimemagazine.com/cranberry-scones/