<<Disclaimer: Verify this information before applying it to your situation.>>
The vegetable is probably Spaghetti Squash. It is very good (& GF) when
boiled and served with a little butter or margerine. It doesn't make a good
substitute for spaghetti as it is not a starch.
Like Eggplant Parmesan, it could be made with tomato sauce to make a new
kind of dish. Enjoy!
Tom