Heat oven to 400° F. Line a baking sheet with parchment paper or aluminum foil.
In a large bowl, combine the flour, baking powder, salt, and baking soda. Using a pastry blender, 2 knives held crisscross fashion, or your fingertips, add the butter to the flour mixture and mix until crumbly. Add the buttermilk and, with a wooden spoon, stir until combined. The dough should be very sticky. Using the spoon or your fingertips, drop heaping tablespoons of the dough onto the baking sheet. Bake until lightly golden and a toothpick inserted in the center comes out clean, 12 to 15 minutes. Serve hot.
Tip: If you prefer, make biscuits from a mix, using cream instead of milk and an extra tablespoon or two of butter.