Pour melted butter in a large iron skillet. ; sprinkle brown sugar evenly in pan. Drain peaches, reserving syrup. Arrange peaches in the sugar mixture. Add enough water to peach juice to make 1 1/3 cups of liquid; add liquid and 3 eggs to cake mix. Mix as directed on the package. Pour batter over the fruit. Bake in a preheated 350 degree oven for 50 or 55 minutes or until cake pulls away from sides of pan. Let stand 5 minutes then turn upside down onto a cake dish or large platter. Serve warm with whipped cream.
If using fresh peaches, peel and slice into a bowl and pour about half a cup of sugar on top and let them sit two or three hours before you begin baking. This will make juice. Add enough water to the juice to make 1 1/3 cups of liquid
You will want to have about three cups of peaches, depends on the size to how many.