Preheat oven to 400˚F (200˚C). Line a large baking sheet with parchment or lightly flour.

In a large bowl, combine the flour, sugar, baking powder, and salt.

Cut in the cold butter using a dough blade, forks, or your fingers until texture becomes coarse and no pieces are larger than a pea.

In a small bowl, beat together egg and 3/4 cup (177 milliliters) buttermilk. Pour into the flour mixture and gently mix using your hands or a wooden spoon.

Slowly add the remaining 1/4 cup (60 milliliters) buttermilk only as needed to bring the dough together.

On a lightly floured surface, gently pat the dough into a circle about 1 inch (2.5 centimeters) thick.

Use a 2 1/2 inch (6 centimeter) round or biscuit cutter to cut out circles of dough. Gently bring together the leftover scraps of dough to cut out more circles.

Transfer to prepared baking sheet. Brush the tops with additional buttermilk.

Bake in preheated oven until golden, 15-20 minutes.