Pour the melted butter into a 10-inch cast-iron skillet or a 9-inch baking pan. Whisk together the flour, sugar, baking powder, and salt until well blended then stir in the milk until smooth. Evenly pour the batter over the butter but do not stir!
Toss the peaches with the cinnamon and ginger then layer on top of the batter. Bake uncovered for 45 minutes or until lightly browned. Serve warm.