Preheat the oven to 425 degrees. In a large mixing bowl whisk together the flour, baking powder, sugar, baking soda, and salt.
Using a pastry cutter, cut the butter into the dry ingredients. The butter pieces should be pea-sized and not overly incorporated. You can also use a cheese coarse grater to grate the butter or a large food processor. Pour the flour and butter in the bowl and pulse a few times.
Stir the flour and butter with a spoon after cutting it to make sure it is evenly dispersed. Make a well in the center.
Pour the buttermilk in the well and gently fold until the dough comes together. Do not over mix.
Dump onto a clean cold lightly floured surface.
Form into a rough rectangle.
Roll or press gently in a rectangle that is about ¼ of an inch thick. Cut into 5-6 pieces. When cutting, do not press down too hard
Stack the pieces and flatten again into a rectangle that is about 1.25 inches thick.
Cut into 8 biscuits that are roughly the same size. (These are supposed to be rustic!)
Place onto a plate or small baking sheet lined with parchment paper. Freeze for 10-15 minutes.
Remove from the cold plate or sheet and place on a large baking sheet lined with parchment paper. Brush the tops with buttermilk and sprinkle with flaky salt if desired.
Bake for 18-22 minutes or until golden brown.