"I don't know what to have for dessert."

Translation: Je ne sais pas quoi prendre en dessert.

[clefairylights]

Why does quoi come before prendre?

[joannecheu1]

Why not "Je ne sais pas quoi avoir pour le dessert" ???

[LLB1964]

Lequel means "which" -- and that would require there to be a specific choice between 2+ choices. "What" here is just referring to any old possible dessert options.

[Dhugal3]

Why not 'je ne sais quoi'?
I'm sure I've seen this before.

[Angela546632]

What is wrong with je ne sais pas LEQUEL ...

[Valkenier]

What's wrong with "je ne sais pas quesque je veux manger pour dessert" Is it correct french but a wrong translation?

[Lucien660983]

First of all "quesque" doesn't exist in French. Maybe you meant "qu'est-ce que", which is interrogative and would be wrong here. "Je ne sais pas ce que je veux manger" would be correct, but not really a literal translation of the English sentence.

[TonyFromKiwiLand]

je ne sais pas ce que d'avoir pour le dessert. Rejected. Reported.