'Frozen' Actress -- I've Made A Fortune Playing Elsa

Don't feel too bad for the young actress who only got a few hundred bucks for her part in "Frozen" -- the biggest animated movie EVER -- TMZ has learned she's made a small fortune in residuals.

We told you about Spencer Lacey Ganus ... the 15-year-old who voiced teenage Elsa in the movie. Her contract guaranteed her $926 for one day of shooting ... but we've learned she actually ended up making 10 TIMES that!

A rep for Spencer tells us ... she's collected more than $10K in residual checks from the flick -- which has hauled in more than $1.2 billion -- and says Disney's expressed interest in hiring her for more voice-over work.

We're told she's putting the cash in a college fund ... where she hopes to -- Let it grow, LET IT GROW!!