Preheat oven to 425°F. In a 2-qt. square baking dish, melt butter in the microwave, about 1 minute.
In a bowl, whisk together flour, sugar, baking powder, and salt.
Add buttermilk and stir until combined.
Spoon dough atop the melted butter in the baking dish. Smooth to an even layer.
Use a bench scraper or paring knife to score the dough in 9 equal squares.
Bake 20 to 25 minutes until golden brown. Serve with jam or honey, if desired.
