Err...it's a hidden room because it's hidden. You don't need anything in there, it's just for fun. I was actually unaware it was possible to get the blocks out from under there. Haha.

The cube you need is in the suspended room with the turrets.

How do I get the boxes out from underneath the cake in the hidden room? I can't place any portals under there or grab them out in any way.

And there are no boxes anywhere else

please help

Pros: Played this map, hehe it was awesome!
Cons: None, really :3
Improvements: Make moar of them :3

Pros: This map looks good and the chalenges are thought out.
Cons: In that first part those cleansers dont reach high enough making people think they can shoot thru it. just add another particle above it and its fixed. Also, because the voice was pretty anoying i turned it off. It was faar from the quality in portal (this probably made me miss some important sounds).
Improvements: Improve the voice. In the normal portal game i even liked it because it realy sounded like a computer voice. in your map i didnt have that feeling. Just try to modify a sentence multiple ways and ask others which one sounds best. Also, try to use less metal in the first room. now that single square made it clear to me what to do. also, i had once that i made the box fell wrong on a button and couldnt get it back (could be me throwing the box too weird inside that hole) :S
Notes: Still, because this map has good puzzles which are pretty hard its worth an 8.