Preheat the oven to 425°F. Line a large baking sheet with parchment paper.
Add the flour, sugar, salt, baking powder, and cold cubed butter to a food processor. Pulse until the mixture resembles coarse crumbs with small pieces of butter remaining.
Add the chopped herbs and pulse a few times to distribute them evenly.
In a separate bowl, whisk together the egg and buttermilk.
Transfer the flour mixture to a large bowl. Pour in the buttermilk mixture and gently stir just until a soft dough forms. Do not overmix.
Divide the dough in half. Gently shape each half into a 6-to 7-inch circle about ¾ to 1 inch thick on the prepared baking sheet.
Cut each circle into 8 wedges and separate the wedges slightly on the baking sheet.
Bake for 10–12 minutes, or just until the scones are lightly golden around the edges and cooked through. Avoid overbaking.
Let cool for a few minutes on the baking sheet before serving or transferring to a wire rack.