Preheat the oven to 425°. In a food processor, pulse flour, baking powder, salt, and sugar to combine. Add the chilled butter pieces and pulse until the mixture resembles coarse crumbs. Transfer to a large stainless steel mixing bowl and add the cheese; toss to combine.

In a small bowl, whisk the buttermilk and egg to combine and drizzle buttermilk over the top; using a fork or a rubber spatula, stir until it forms a moist, slightly tacky dough; if the dough seems dry, add a few more tablespoons of buttermilk. Do not overwork! (Alternatively, cut the butter into the flour in a large mixing bowl using a pastry cutter or two forks).

Transfer the dough out onto a lightly floured surface, dust the top of the dough with a bit more flour and bring it together gently into a rough ball. Pat the dough into a rectangle about ¾'' thick. Then, using a sharp knife or bench scraper, cut the dough into four pieces.

Stack dough pieces on top of one another, sandwiching any loose dry bits of dough between layers, and press down to flatten.Lift the dough with a bench scraper and lightly dust the surface with flour to prevent the dough from sticking.

Lightly flour the top of the dough, then lightly pat or roll out the dough into a ¾" thick rectangle ( do not overwork it, or the biscuits will be tough).

Dust a 2-½-inch round biscuit cutter with flour and cut out rounds. Alternatively, use a knife to cut the biscuits into 8 rough squares. Re-stack any scraps, re-roll, and cut out more biscuits. Repeat this process until the dough is gone.