2 cups all-purpose flour, plus more for dusting the work surface
2 teaspoons baking powder
1/2 teaspoon baking soda
1/2 teaspoon kosher salt
(1 stick) cold unsalted butter
1 cup shredded sharp cheddar cheese
8 slices bacon, cooked and finely chopped (about 1 cup)
4 medium scallions, white and light green parts, finely chopped
1 cup buttermilk
Arrange a rack in the center of the oven and heat to 230 degrees C.
Place the flour, baking powder, baking soda, and salt in a medium bowl and whisk to combine.
Place a box grater over a small piece of parchment paper or the butter’s wrapper. Grate the cold butter on the large holes of the grater. When you get down to a small nub of butter, chop that nub into 5 to 6 small pieces. Use the piece of paper as a sling to transfer the butter from the grater to the flour mixture.
Add the cheese, bacon, and scallions. Stir with a spatula or wooden spoon until well combined. Quickly pour in the buttermilk and stir with a wooden spoon until the dough comes together and pulls away from the sides of the bowl.
Transfer the dough to a lightly floured work surface. Pat the dough into a 1-inch thick rough rectangle about the size of a sheet of paper with a short side facing you. Sprinkle the dough with a little more flour if needed. Fold the dough onto itself vertically and pat it down (this makes the flaky layers of the biscuits). Fold the dough in half horizontally. Pat it back down to the same size rectangle. Repeat the folding and patting for a total of 8 to 10 folds. The dough should be a little springy.
Pat the dough into a 1-inch thickness. Use a 3-inch round cutter to cut as many biscuits as you can (about 6). Gather the scraps into a rectangle, refold, and pat down before cutting the remaining dough (you’ll likely get about 4 more, for a total of 10 biscuits).
Transfer the biscuits to a rimmed baking sheet, they should touch each other but not the sides of the pan. Bake until golden brown, 15 to 18 minutes. Immediately transfer the biscuits to a clean kitchen towel to keep warm for serving.