In a large mixing bowl, whisk together all-purpose flour, baking powder, and sea salt until well combined.

Dice cold unsalted butter into small cubes, then add to the dry ingredients and mix until the mixture resembles coarse crumbs.

In a separate bowl, whisk together cold buttermilk, a beaten egg, and melted butter until just combined.

Make a well in the center of the dry ingredients and gently pour in the wet mixture. Stir until just combined.

Turn the dough out onto a floured surface, flatten into a rectangle, then sprinkle cheese and herbs over the dough. Fold the dough over itself three times.

Preheat oven to 400°F (200°C). Cut out scones using a biscuit cutter and transfer to a parchment-lined baking sheet. Brush tops with egg wash.

Bake for about 18 minutes, or until the scones are golden brown and puffed.

Allow to cool on a wire rack for a few minutes before serving warm or at room temperature.