English Scones with Zante Currants

Ingredients

• 3/4 Cup Buttermilk
• 2 Large Eggs, chilled, plus one egg, well beaten
• 3 Cups Unbleached All-Purpose Flour, plus more as needed
• 1 Tablespoon Baking Powder, plus 1 teaspoon
• 2 Tablespoons Superfine Sugar
• 1/4 Teaspoon Kosher Sea Salt Flakes
• 1 Dash Ground Nutmeg
• 10 Tablespoons Unsalted Butter, chilled and cut into 1/2-inch cubes
• 1/2 Cup Dried Zante Currants
• Turbinado Sugar , for finishing (optional)