There's no rule about that, you can ask either Pasta? or Pastan? depending on what you mean, just like in English. We're in an A/B test right now so I can't know for sure which TTS you're hearing, but if you've got the new one like I have, the final n is indeed a bit weak and could be easy to miss.
Honestly, I think that this could be used in a restaurant setting... As to ask about the pasta. Like in fancy establishments that only have two or three options a night, and one was pasta. You would ask about the pasta( "Pastan?"). Just a guess tho, could totally be wrong.