Memento Nubla Trophy
You have completed every drawing of the Museum.
This trophy requires that you get all of the collectibles marked as "Dreamt Objects" when you pick them up, all of which have a trophy tied to them. If you have collected all of the collectibles up until this point, this means you will have completed every drawing (the paintings of the museum will be full of line drawings of the paintings named in each trophy description). The trophy will pop after the credits, not upon collecting the last collectible, along with the platinum.
However, if you missed one or more, you'll need to play the game again at least up until the point where the last collectible you need can be found, since there's no chapter select. Once you have your last collectible and the corresponding trophy tied to it, quit the game. Upon restarting, this trophy will pop, along with the platinum.