When baking a dump cake at 350°F, the average baking time is around 45 to 50 minutes. However, baking times can vary depending on the specific recipe and the size of the baking dish used. It's always a good idea to check for doneness by inserting a toothpick or a cake tester into the center of the cake. If it comes out clean or with a few crumbs, the cake is ready.