Melt ½ cup butter in 13 X 9 inch baking dish.
Combine 1 cup flour, 1 cup sugar, 1 tablespoon baking powder, and 1 cup milk stirring just until dry ingredients are moist.
Pour over butter in baking dish.
In a medium sauce pan bring to a boil 1 cup sugar and 4 cups peach slices (stir constantly).
Pour over batter (do not stir together).
Sprinkle with cinnamon if desired.
Bake at 375 degrees for 45 minutes.