Is this supposed to be prepared on site or brought?
In any case, it would be a mistake to go too simple. With all due respect to jessiquina, a really perfect brulee might impress another a pastry chef with its sheer perfection (and if jessi says so, it would!); but it's not really what an executive chef is looking for. Espcially not a joint with a star.
You want to demonstrate command of a range of techniques, imagination, decorative skills, and plating -- at least.
I am not, never have been, and have never even been confused with a pastry chef. That said, I'd bring at least two different "bread basket" loaves with me to the interview (one of which should be pain de campagne).
For the desserts, I'd do a sampler or possibly a "trio" on one plate -- at least one of them "classic," at least one very much au courant, at least one complex, at least one dead simple, one based on chocolate, one on vanilla and/or fruit, and one on citrus.
If it's restricted to one thing, it should not only be perfect (perfect goes without saying), but should also be something not many other people could do at all, not on their best day.
FWIW, forget the lamb.