In the case of the original sandwich maker, Rangos, clearly not. He was making his pimento cheese and selling it in his store before the Masters ever hired him.
In the case of the second sandwich maker, Godfrey, who replaced Rangos and developed his pimento cheese recipe for the Masters, probably not.
First of all, work for hire concerns who owns the copyright to something and recipes are not subject to copyright.
It is possible, though, that there is some expression in the way that he wrote the recipe that could be copyrighted, so let's say the Masters wants to make a work for hire argument that they own the copyright of that.
To be a work for hire, something must either be (1) made by an employee within the scope of their employment, or (2) fall into one of several categories and be declared a work for hire by the parties in a written instrument signed by them.
It doesn't sound like the pimento cheese provider is an employee of the Masters. He sounds more like a contractor. That would take out #1 of the two ways something could be a work for hire.
As far as #2 goes, first they have to explicitly have said in their signed written contract that the expression of the recipe will be a work for hire. That seems unlikely.
But let us say they did, and let us assume that the particular expression of the recipe counts as an instructional text. Let's say that means that the Masters owns the copyright on that particular expression of the underlying, uncopyrighted, recipe.
So what?
That just means they get to stop people from making and distributing copies of that text. It doesn't give them any power to compel someone who has a copy to turn it (or a copy of it) over to them.