Step 1

Preheat the oven to 425° and position a rack in the lower third of the oven. In a large shallow bowl, whisk the flour, baking powder, baking soda and fine salt. Add the chilled butter and use a pastry blender or 2 knives to cut the butter into the flour until it is the size of peas. Stir in the buttermilk just until the dough is moistened. Lightly dust a work surface with flour. Turn the dough out onto the surface and knead 2 or 3 times, just until it comes together. Pat the dough into a 1/2-inch-thick disk.

Step 2

Using a floured 2 1/4-inch round cookie cutter, stamp out biscuit rounds as closely together as possible. Gather the scraps and knead them together 2 or 3 times, then flatten the dough and stamp out more biscuit rounds. Pat the remaining scraps together and gently press them into a biscuit.

Step 3

Transfer the biscuits to a large baking sheet and brush the tops with the melted butter. Lightly sprinkle the biscuits with a few grains of flaky salt and chill until firm, about 10 minutes.

Step 4

Bake the biscuits for 20 minutes, or until golden. Let the biscuits cool slightly on the baking sheet before serving.