Preheat your oven to 425°F (220°C) and grease a 9x13-inch baking dish.
In a large mixing bowl, whisk together the flour, baking powder, salt, and sugar until well combined.
In another bowl, mix the melted butter and buttermilk together. Pour this mixture into the dry ingredients and stir until just combined. Be careful not to overmix; a few lumps are okay.
Gently fold in the blueberries, being careful not to break them.
Pour the melted butter into the prepared baking dish, spreading it evenly across the bottom.
Drop spoonfuls of the biscuit dough into the melted butter, spacing them evenly apart.
Bake in the preheated oven for 20-25 minutes, or until the tops are golden brown.
Remove from the oven and let cool for a few minutes before serving warm.