There isn't hard evidence as to when dump cakes were first developed, but the earliest mention seems to be in the 1920s when from-scratch recipes for dump cakes were believed to have been seen.

The church cookbook "Carolina Cookery: From Quaker Kitchens" was written in 1924 and contained a Dump Cake recipe created ...

Get Ree's Apple Dump Cake recipe. Did you love Hamburger Helper back in the day? Well, you can make an even tastier and healthier version from scratch in one pot with just ten minutes of prep time.