Preheat oven to 350 degrees F

Lightly toast bread slices and place on a cookie sheet lined with parchment paper or aluminum foil for easy clean up. Top each slice of bread with a slice of ham; top ham with a slice of cheese. Using an electric mixer, beat egg whites in a mixing bowl until fluffy and stiff peaks have formed. Mound egg whites attractively atop each slice of bread, forming a well in the center. Slide an egg yolk into the center of each egg white well. Place cookie sheet in the center of a preheated 350 degree F oven and bake for 10-15 minutes (depending on the accuracy of your oven), or until the egg whites are lightly golden and egg yolks are just set (egg yolks will be over-easy to over-medium in doneness). Remove cookie sheet from oven. Using a large, sturdy spatula, plate Eggs in a Cloud immediately. Serve warm.