Combine the flour, white sugar, baking powder, salt, and baking soda in a food processor. Pulse for 10 - 20 seconds.
Add the butter and rub it flour and butter gently with your fingers until it has a bread crumb like texture. This can be done in a food processor as well. Pulse the butter and dry ingredients for 20 - 30 seconds minutes.
Add chocolate chips, walnuts, and buttermilk in small batches. Bring the dough together with your hands. If the dough is still too crumbly, stir in more buttermilk a tiny splash at a time, but try to avoid over mixing. In a food processor, it comes together in a minute.
Transfer the scone dough to a bowl. Cover with a cling foil and keep it in the refrigerator for 5 – 10 minutes. Meanwhile, line a pie dish or baking sheet with parchment paper. Preheat oven at 180 degrees Celcius.
Transfer the dough into the pie dish and pat it into an 8-inch (20 cm) round with a thickness of ½ inch. Use a pastry scraper or knife to divide the dough into 8 big size wedges or 12 sleek wedges. Brush the tops of each wedge with the melted butter & generously sprinkle with light brown sugar.
Bake the scones for 20 - 25 minutes, or until the tops are golden brown. Re-cut the slices immediately with a pastry cutter if need be.
Cool the scones completely on a rack before storing. Serve with a drizzle of vanilla icing or a dusted with sugar.