Preheat the oven to 350°F
Melt 1/2 cup butter in a 9×13-inch baking dish
In a bowl, mix 1 cup flour, 1 cup sugar, 1 tablespoon baking powder, and 1/2 teaspoon salt
Stir in 1 cup milk until smooth
Pour the batter over the melted butter
In another bowl, mix 4 cups sliced peaches, 1/2 cup sugar, and 1 teaspoon cinnamon
Spoon the peach mixture evenly over the batter
Bake for 40 to 45 minutes until golden brown
Let cool slightly before serving