Hi all. I made a bread pudding in the oven last week and baked it for an hour until it was brown and rounded on top. However, after I took it out, it did not take long for it to droop back into the pan. How can I avoid this?

My grandma R.I.P. had an awesome bread pudding; it was by far the best I've ever tasted…there's only one problem, she never showed me how to make it. From eating it I knew that it at least had the following ingredients: