I generally just eat dinner leftovers for breakfast, but do make a lot of egg mcmuffin sandwiches for DH and DSD. I wrap them in foil and stick them in the fridge, then they throw them in the oven at 350 when they get up and they are ready to go in 20 minutes to a half hour.
I cook my eggs for them in a muffin top/whoopie pie pan - just spray with non stick, crack the eggs in, season, and bake in the oven until done. I usually puncture the yolk with a knife so that they will spread just a bit so that the resulting egg patty is more flat.
I mix them up and make non-traditional ones depending upon what is on hand. Last week we had seared steak, caramelized onions and provolone cheese on the egg mcmuffins. This week is leftover corned beef and swiss. Next week is either going to be pizza, with pepperoni, sauce, and mozzarella, or chicken and spinach with pesto and parm/mozzarella.