Variations
There are so many things you can do to jazz this up.
Place a teaspoon of pesto in the hold before dropping in the egg.
Add a tablespoon of shredded cheese on top of the egg, and under the toasted circle.
Cook a piece of bacon ahead of time, crumble it into the hole before you add the egg.
You could make this in a Panini machine; I'm sure, though I've never tried it.