Whisk the flour, salt, pepper, and baking powder together in a large bowl. Add the butter to the flour mixture and rub it with your fingertips until all the butter is coated with flour and you have a crumbly mixture. Place the bowl in the freezer as you prepare the wet ingredients.
Whisk the ½ cup buttermilk and the egg together in a measuring jar. Pour the mixture over the dry ingredients, add the cheese and herbs, then mix together until everything is moistened. I start with a rubber spatula and end with my hands. To make the dough easier to work with, you can rest it in the fridge for 10-15 minutes, if desired.
Preheat the oven to 400°F.
Dump the dough onto a lightly floured work surface. Flatten it into a disc about 1 inch thick and 8 inches in diameter, then flip it over. Irish scones are traditionally round. Cut them out with a floured 2 ½-inch diameter cutter or drinking glass. Gently reform the scraps, pat them flat, and cut again. Hand-shape the final scraps into the last scone.
Arrange the scones 2-3 inches apart on a lined baking sheet and brush the tops with buttermilk. If you won’t be baking them immediately, keep them cold in the fridge until you put them in the oven. Rest them in the fridge again for 10-15 minutes for maximum rise, if desired. Bake for 20-26 minutes or until lightly browned on top.