In Super (2010), I noticed the weird concept of flashbacks within flashbacks within flashbacks.
Which was the first Hollywood movie with the same concept?
As mentioned in the Wikipedia article on narrative uses of flashbacks:
IMDB flaged also Enter the void (2009) with this technique. Seems that only these movies used this kind of brain teaser. As I found only these titles, i can answer your question saying that Passage to Marseille (1944) was the first movie using this technique. If you are interested you can give a look to the detailed plot here (SPOILER) looking how the flashbacks were actually mixed.