How to Make It
Preheat oven to 425°F. Line a large rimmed baking sheet with parchment paper. Break cheese into large chunks; transfer to a food processor, and pulse until coarsely ground, 16 to 20 times. (You should have a little over 12/3 cups ground cheese.) Reserve 2 tablespoons cheese.
Stir together flour, sugar, pepper, and 1 cup ground cheese in a large bowl. Cut butter into flour mixture using a pastry blender or your fingers until mixture resembles coarse crumbs. Stir in buttermilk until a shaggy dough forms.
Transfer dough to a floured work surface. Pat into a 1-inch-thick rectangle, and cut into quarters; stack quarters on top of each other. (Dough will be crumbly at first but will come together as you work.) Pat stacked dough back into a rectangle. Repeat cutting and stacking 2 more times. Roll or pat dough into a 3/4-inch-thick rectangle (about 8 1/2 x 10 inches). Cut rounds out of dough using a 11/2-inch round cutter, pressing straight down, without twisting cutter. (You’ll have about 35 biscuits; discard dough scraps.)
Sprinkle 2/3 cup ground cheese in a 12- x 8-inch rectangle on prepared baking sheet. Arrange biscuits 1/2 inch apart on cheese. Freeze 10 minutes. Remove from freezer; brush biscuit tops evenly with egg. Sprinkle lightly with pepper and reserved 2 tablespoons ground cheese.
Bake in preheated oven until biscuits are golden brown, 12 to 14 minutes. Serve warm, or let cool to room temperature, about 30 minutes.