Preheat oven to 350 degrees F. Lightly coat a 9x13in dish with cooking spray.
Add the peaches to the dish in an even layer.
Roll each of the cream cheese cubes in the brown sugar to coat and scatter evenly among the peaches.
Sprinkle the cake mix (only the powder, do not prepare cake mix) over the top of the peaches and cream cheese in an even layer. Spread the butter slices evenly over the top, then sprinkle with the remaining brown sugar (use more if needed).
Bake for 40 to 45 minutes, or until the center is slightly bubbling. Let cool for at least 10 minutes before serving. Enjoy!
If peaches are not in season, substitute with canned peaches! Use 2 (15oz) cans of peaches in light syrup. Drain most of the juices before adding to the pan.