Place cast-iron pan over a fire and add butter. In a large resealable bag, combine peaches, cinnamon, cornstarch, salt and sugar. Seal bag and toss to coat evenly. (This step can be done before you depart.)

In another resealable bag (or bowl if you’ve got one) add biscuit mix and milk and knead the bag or stir to mix well (eliminating any clumps).

Once butter is melted, add fruit mixture to the skillet and top with the biscuit mixture. Sprinkle remaining sugar on top. Cover with foil and cook until biscuit is flakey or lightly browned, about 45–50 minutes.