Pour melted butter into an 8" square baking dish. In a medium bowl, stir together granulated sugar, flour, baking powder, and milk.
Pour the mild mixture on top of the melted butter. Do not stir. Without mixing, arrange the peaches evenly on top of the batter. Evenly sprinkle the brown sugar over the cobbler.
Bake for 40-45 minutes, until top is golden brown.