Prepare fire as directed below. Mix peaches, cinnamon, and 1/2 cup sugar in a 4- to 6-qt. cast-iron camp dutch oven.
Stir pancake mix, butter, egg, remaining 1/4 cup sugar, and 1/4 cup water in a medium bowl to make a thick and chunky batter. Drop 4 evenly spaced heaping spoonfuls over peaches. Cover.
Arrange coals for top and bottom heat cooking and cook, checking every 10 minutes, until batter is puffed, firm, and starting to brown, 20 to 25 minutes. Serve portions with whipped cream.
How to Use a Dutch Oven
Prepare the fire. If you have a campfire going, move any large pieces of still-burning wood to the side and level out your hot coals to fit the size of the dutch oven. If the campground doesn't allow wood fires, burn 50 charcoal briquets till they're mostly gray, 10 to 15 minutes, and spread into an even layer the size of the dutch oven.
Set up the oven. For many recipes, you just set the dutch oven on top of the hot coals ("bottom heat cooking"). But there are times when you'll need to heat both the top and bottom of the oven. Just scrape about half the coals to the side and arrange the rest in a circle the size of the dutch oven's outer edge. Set the oven on top of the circle of coals, then pile the rest of the coals on top of the lid.
Start cooking. Lift the dutch-oven lid occasionally to check the food and temperature. To decrease the heat, scrape away some fuel. To increase the heat, or to cook longer than 45 minutes, add 6 to 10 new briquets or more wood embers (from that still-burning wood you moved to the side of your firepit) every 30 minutes.
Note: Nutritional analysis is per serving.