Preheat oven to 350ºF.
Lightly spray a 9x13-inch pan with cooking spray.
Dump 2 cans of peaches with syrup into baking pan. Drain the third can and add peaches to pan.
Sprinkle peaches with cinnamon. Top peaches with dry cake mix - sprinkle evenly over the top of peaches.
Drizzle cake mix with butter.
Bake 50 minutes to 1 hour or until top is golden brown and fruit is bubbly.
Enjoy warm with ice cream!