Vilte I don't remember what it was called but I do remember that it was a lot.
That would be a Francesinha!
I ate it for the first time in Porto a few years ago and, like you said, it is a lot.
But, we decided to experiment and make a vegetarian version, including that sauce which traditionally has bacon fat and beef stock in it, and managed to come up with something that (I think) is pretty great.
You can find the recipe for it here: Meat Free Francesinha