I put "what's for dessert" instead of "What are we having for dessert." I guess it's kind of hard to test out of things if you don't know exactly what they want.
I used the wrong pronoun too. Because this literally means:
- (As for) desert, what (are you/we) eating?
Ah! I was really confused why "dessert" did not have an object marking particle. Now I understand it better! Thanks!