Preheat your oven to 450°F (230°C).
In a mixing bowl, combine flour, baking powder, sugar, and salt.
Stir in the buttermilk until just combined; do not overmix.
Pour the melted butter into an 8x8-inch baking dish, ensuring the base is fully coated.
Pour the dough over the butter, spreading it evenly with a spatula.
Use a knife to score the dough into 9 squares for easier serving.
Bake for 20-25 minutes or until golden brown and fluffy.
Allow to cool slightly before serving.