No, this sentence is a question about what you like to have for dessert in general, it's not an offer to have a dessert now (that would be «Що ви хо́чете на десе́рт?»)
The verb 'хощити' is "to want, to will", not "to would like". OCS 'би- хощили' or 'би- желѣли' (I 'm not sure how this construction has developed in Ukrainian) would be "to would like".
Well, those are just different things.
We might be walking down the street and just chatting about our preferences in food, and I ask you, "What dessert do you like"? (and not want right now)