Preheat the oven to 400℉. Spray a 9x13 baking dish with nonstick cooking spray.
Add all of the peaches in an even layer on the bottom of the prepared pan.
In a medium bowl whisk together the cake mix and cinnamon until everything is evenly distributed.
Pour the mixture evenly over the top of the peaches and press the mixture down with your fingers.
Grate butter over the top of the cake mix mixture in an even layer.
Bake in the preheated oven for 40-45 minutes or until it is golden brown.
Remove from the oven and serve with whipped cream or vanilla ice cream!
