Sprinkle the dry mix evenly over the top until you can't really see the peaches underneath anymore. You're not stirring anything, just covering. It'll look a little strange at this point, like a layer of powder sitting on fruit, but that's exactly right.

Cut it into small, bite-sized chunks and scatter them across the surface of the cake mix, spreading them out as evenly as you can so the butter reaches most of the top. Some dry spots might still happen that's fine, more on that below.

I'm generous here because I really love cinnamon with peaches. If you're more conservative, start light you can always add more once it comes out, but you can't take it away.