In a large mixing bowl, whisk together Add flour (2 1/2 cups), baking powder (4 teaspoons), sugar (4 teaspoons), and salt (1 1/2 teaspoons) in a medium bowl until evenly combined.
Add buttermilk (2 cups) and mix until almost combined. Do not overmix at this point.
Place an 8X8 baking dish on a rimmed baking sheet. Pour melted butter (1/2 cup) onto the baking dish.
Transfer the dough to the baking dish, on top of the butter. Use lightly greased (with butter) hands or a spatula to evenly spread the dough to the edges of the baking dish.
Cut the unbaked dough into 9 even squares. Bake in preheated oven until the top is golden brown, about 22-28 minutes.