Preheat your oven to 180° C (350° F), get out a 7x11 inch baking pan.
Melt the butter in a large non stick pan, when hot, cook the onion until soft but not browned.
Spread onions in the bottom of the baking pan.
Top onions with egg slices.
Top eggs with the cheese.
In a saucepan, add the soup, milk, and black pepper, heat, stirring until the mixture is smooth.
Drizzle the soup mixture over the casserole, be sure some seeps down to the bottom.
Arrange bread slices on top, overlapping them along the center of the pan.
Bake for 20 minutes or until hot, then broil to toast the bread.
Serve and enjoy.