Begin by dicing cold unsalted butter into 1/4-inch cubes and place them in the freezer for about 10 minutes.

In a large bowl, whisk together all-purpose flour, granulated sugar, kosher salt, baking powder, and baking soda. Fold in shredded cheddar cheese and minced chives.

Add the chilled butter cubes into the dry mixture and mix until it resembles clumpy sand.

Gradually pour in cold buttermilk with a stand mixer running on low. Mix until the dough just begins to clump together.

Turn the dough out onto a floured surface and press it into a rectangle. Fold the dough into thirds and press down. Repeat this folding and pressing process three more times.

Form the dough into a 9-inch square about 1 inch thick, cut it into 9 equal squares, and refrigerate for 30 minutes.

Preheat oven to 450°F (232°C). Brush the tops of the chilled biscuits with buttermilk and sprinkle with sea salt. Bake for 18-20 minutes until golden brown.