I've had great success with the cannele recipe in Toothache Magazine: https://toothachemagazine.com/collections/print-issues/products/toothache-issue-04-preorder. It's not free, unfortunately, but it was developed with a lot of testing and trial and error, which is always fun to read about. More labour intensive, but never had any failure with it in my home kitchen. I do use copper molds though along with a mixture of beeswax and clarified butter to line the moulds. No need for a hot steel base.