This makes a great breakfast, brunch or a quick treat to make when company shows up. I created this recipe and have been making it for 40 years. I don't normally use a recipe and eyeball it so this recipe can be made as you like it and the amount you want to eat. Once you make it once you will figure out how to make it for just one person or a few.
Separate one egg. Beat egg white until stiff (as if making a meringue). You will know it is done enough if you hold the bowl upside down and it stays in the bowl!!
Cut bacon into small pieces and fry until crispy. Remove bacon and drain on paper towel. Cut mushrooms (portobello or button work good). Fry mushrooms in bacon fat or butter. Drain on paper towel.
With the remaining 2 eggs and extra egg yolk, prepare an omelette, adding bacon and mushrooms. I don't add salt as there is enough in the bacon but if you want you can add salt and pepper. Place omelette on top of toasted and buttered bread. Top with egg white meringue and top the meringue with grated cheese (cheddar is best). Place toasted sandwiches under grill until meringue is golden and cheese is melted. You can also put a slice of tomato on the bread before you add the omelette.