In a large bowl, whisk together the flour, baking powder, salt and sugar. Cube or grate the cold butter on top of the dry ingredients, and then cut it in using a pastry cutter or fork. Stir in the buttermilk, and gently work the mixture until combined to form the dough.
On a floured surface, flatten and fold the dough onto itself three times. Flatten the dough out to a thickness of approximately one-half inch.
Using a 3-inch round cutter, cut the dough and place on a parchment-lined baking sheet. Brush the tops with cream or melted butter, and sprinkle a pinch of natural sugar over each.
Bake the biscuits until puffed and golden, 15 to 20 minutes, rotating the tray halfway for even baking and coloring. Serve the biscuits warm.