Preheat your oven to 425°F (220°C).
In a large mixing bowl, combine the flour, baking powder, salt, and sugar.
In another bowl, mix the cold buttermilk and melted butter together.
Pour the wet ingredients into the dry ingredients and stir until just combined.
Pour the batter into a greased baking dish.
Bake for 15-20 minutes, or until the top is golden brown.
Remove from the oven and brush the tops with melted butter.
Let cool slightly before serving.