I am a big fan of shirred eggs, too. They can be so versatile.
I have prepared them several different ways. As far as I am concerned, if it fits in the ramekin it is good. I don’t use a water bath, I just place them on a cookie sheet.
Some of the different things we have used to flavor our shirred eggs are combinations of bacon, ham, sausage, cheddar cheese, Parmesan cheese, and Swiss cheese.
We have also flavored them with different herbs, cream cheese with herbs, onions, chives, and garlic.
One fun idea was when we made pizza shirred eggs, a creation of our son. We used Italian seasoning, mozzarella cheese, bits of diced pepperoni, and a touch of pizza sauce.