Cheddar, Jalapeño & Chive Biscuits

INGREDIENTS

• 3 cups all-purpose flour
• 1 tablespoon granulated sugar
• 4½ teaspoons baking powder
• ¾ teaspoon cream of tartar
• ¾ teaspoon salt
• ¾ cup buttermilk, plus more for topping
• 1 egg
• 3 ounces sharp cheddar cheese, diced small
• 1 jalapeño, seeded and minced
• 3 tablespoons minced chives
• ¾ cup unsalted butter, cold and cut into small cubes
• Coarse sea salt for topping