In a bowl, mix the mayo, garlic powder, scallions. Season with salt and pepper to taste (add more garlic powder to taste if desired). Toast the bread and spread the mayo on each slice.
Heat the oil in a non-stick pan over low-medium heat. Add in the ham and sauté for 2 minutes. Add in the eggs and cheese. Move the eggs around the pan. Once they start to become firm and fluffy but still a little moist remove from the heat. Season with salt and pepper.
Serve the eggs over the toast with plums. Garnish with scallions.