"The pasta, please!"
Lundgren8 is spot on, just wanted to add that you could say "Kan du vara snäll och skicka pastan?" (normal, but needlessly polite) or "Kan du snälla skicka pastan?" (this sounds childish though, but otherwise same as the one before).
"Kan du skicka pastan?" followed by a "Thanks." is probably how I'd do it. "Pastan, tack!" is a bit too frank in my opinion. :P
I think what they're trying to say above is that, while "snälla" might be grammatically correct, it isn't idiomatically what most native speakers would say in that situation. Languages don't always follow the rules, not even their own! In cases like this, sometimes it's just best to accept what the native speakers are telling us even if it doesn't seem to make sense.
See, languages are not constructed as direct translations of English. Each language evolved differently, with different needs and characteristics. "Tack" doesn't mean "thanks" or "please". In some cases where an English speaker would say "thanks", and some other cases where they would say "please", Swedes say "tack". It's a different word. I prefer thinking about languages in that way, independently.