3 cups all-purpose flour
1 Tbsp granulated sugar
4 1/2 tsp baking powder
3/4 tsp cream of tartar
3/4 tsp salt
3/4 cup cold buttermilk, plus additional for topping
1 egg
3/4 cup cheddar cheese, cut into small cubes (Less cheese may be used, if desired.)
1 medium jalapeño, seeds removed as desired, small dice
3 Tbsp chopped chives
3/4 cup unsalted butter (1 1/2 sticks)
Coarse sea salt for topping
Place the oven rack in the center of the oven and preheat to 425 degrees. Line two baking sheets with parchment paper and set aside.
In a large bowl, whisk together flour, sugar, baking powder, cream of tartar and salt. In a small bowl, whisk together buttermilk and egg.
Cut the butter into the flour mixture using your fingers or a pastry blender, breaking the small cubes into small bits. Once the butter is well incorporated into the flour mixture, the flour will resemble coarse meal. Some chunks will be the size of small pebbles, others will be the size of oat flakes.
Toss the cheese mixture into the flour mixture. Create a small well in the center of the flour mixture and add the buttermilk mixture all at once. Toss together with a fork making sure that all of the flour bits are moistened by the buttermilk. Mixture will be shaggy. Dump the biscuit dough onto a lightly floured counter and knead for 8-10 minutes, just to bring it together into a 1 1/2 inch thick circle.
Cut the biscuits out with a 2 1/2 inch circle biscuit cutter or use a knife to cut the dough into squares. Gather dough scraps, knead lightly and cut out more biscuits. Repeat until dough is gone. Place biscuits on prepared baking sheets, brush with buttermilk, sprinkle with sea salt and bake for 12-15 minutes.
Biscuits are best the day that they are made but they can be stored, wrapped, at room temperature and served the next day.