Preheat oven to 425°F (220°C). Line a baking sheet with parchment paper.
In a large mixing bowl, sift and whisk together the flour, sugar, baking powder, and salt.
Add the cold, cubed butter to the dry ingredients. Using a pastry cutter or your fingertips, work the butter into the flour mixture until it resembles coarse crumbs.
In a small bowl, beat the egg and buttermilk together. Pour into the flour mixture and stir until just combined. If using, fold in the raisins.
Turn the dough out onto a lightly floured surface and gently knead it a few times to bring it together. Do not overwork the dough.
Pat the dough into a round about 1 inch thick. Using a 2 1/2-inch biscuit cutter, cut out the scones and place them on the prepared baking sheet.
Gather any remaining dough scraps, re-pat, and cut out additional scones.
Bake for 18-20 minutes, or until the scones are golden brown on top.
Remove from the oven and let cool slightly on a wire rack before serving.