The initial press stories overstated the patent application. McDonald's is not trying to patent the sandwich. They are, however, patent the process involved in making a sandwich. From the application itself:
In accordance with another aspect of the invention, a method of making a sandwich composed of at least a bread component and sandwich garnish is provided, comprising placing sandwich garnish material on a sandwich assembly tool. The sandwich assembly tool has a region for holding sandwich garnish material to be applied to a bread component of a sandwich and the tool comprises at least one cavity. Sandwich garnish is placed in the cavity, a bread component is placed over and adjacent the cavity and thereafter the sandwich assembly tool is inverted while the bread is adjacent and covering the cavity to cause the sandwich garnish to be deposited from the cavity to the bread component. In a sandwich assembly tool having two cavities, sandwich garnish is placed in both cavities, and the sandwich assembly tool is inverted while a bread component completely covers both cavities to cause the garnish in the cavities to be deposited on the bread component.In other words, you take some meat and/or cheese, vegetables, and condiments and squish them between two pieces of bread. Using the sandwich assembly tool, of course.
It is one thing to patent a tool. It is quite another to patent sandwichmaking.