Great recipe - received a similar one from a sister-in-law then lost track of it. This seems to be the closest to that family favorite.
I will note just a couple of changes from my original.
#1 There was no baking powder in mine. The bars were a bit heavier but seemed to match very well the texture of the frosting.
#2 My recipe called for 1 cup chocolate chips AND 1 cup mini marshmallows added to the boiled mixture. It took a bit longer to get everything melted but the results were luscious.
These bars are as close as you can get to a combination of cake and candy bar. : )