E.A.
My opinion, but I also agree that you might want to talk to a lawyer:
Typically, they *should* compensate him for using his recipe, but it would only be a one-time compensation. What he creates there, like another poster said, belongs to the company, as he is acting as an agent for the company.
My husband is in charge of coming up with the burger special every week at the restaurant where he works, he is compensated for it with gift certificates he can use in-house. He has created a lot of dishes for the restaurants he has worked for, and benefited through raises and other perks.
However, this does not in any way prevent your husband from using that recipe elsewhere or for profit outside the company, unless he signs a non-compete agreement--which he should NOT sign. When we had our own restaurant, my husband used many of the recipes he developed for other owners, and there wasn't a damn thing they could do about it.