Preheat the oven to 450° F (230° C) and place a rack in the middle of the oven.
If grating the butter, do so ahead of time then chill it.
In a large bowl, add the dry ingredients, the flour, baking powder, baking soda, and salt then fluff to mix with a fork.
Add the grated butter or use a pastry blender to cut the butter into the flour mix. Using your fingers to blend the butter in works as well, as does a food processor but use the processor very minimally.
When the butter is about pea-sized, add the cheese and optional bacon and scallions, mixing gently to combine with the same fork.
Add the cold buttermilk and with the fork or a spoon, stir lightly until barely combined. The dough will be lumpy and some flour not mixed in.
Lightly flour a work surface and dump the dough onto the surface. With light hands, push the dough together to form a mostly cohesive piece, then flatten the dough to about 1” thick. Fold the sides into the middle as if folding a letter, fold over in half and repeat for about 6 to 8 times. If the dough warms too much, place in the refrigerator for about 5 minutes.
Flatten the dough to about 1” thick and using a 3” circular cutter dipped in flour, push the cutter straight down through the dough without twisting. Pull the scraps together, flatten and fold one time, cutting circles and repeat.
Place the biscuits on a cookie sheet, either touching each other for soft sides or with space between for more baked sides. Bake for 15-18 minutes, until golden. Remove the biscuits from the sheet and place in a towel to keep warm.