Are you a fan of a 'movie within a movie' in Horror Films?

I've just been to see ‘Teenage Sex and Death at Camp Miasma’ and <<no spoilers>> it contains a movie within a movie. As in, the characters are watching a movie, then we go inside that movie and view that film. I remember seeing that in a movie that I thought had a similar theme called ‘The Final Girls’ - and they actually got trapped in a kind of ‘Sleepaway Camp’ / ‘Friday the 13th’ 70/80s Slasher. Can you think of any more horror films that do that?

There is a good list of similar films on Letterboxd - https://letterboxd.com/film/teenage-sex-and-death-at-camp-miasma/