Into a bowl, add the chicken fillets. To season them, add the salt, the black pepper, the oregano, the garlic and the lemon - you can add any other spices you like - and mix very well. Set aside in the fridge.
Boil the potatoes just in water, mash them well and set aside.
Into a saucepan, add the butter and let it melt. Add the mashed potatoes, the milk and the salt, mix nonstop into a mash until you notice it's no longer sticking to the bottom of the pan.
Get the chicken fillets we've set aside and first dip them in the eggs, then coat them in the breadcrumbs, to make a nice breading. Fry them over medium heat.
Cover the bottom of a glass baking dish with tomato sauce, spread well, add the fried chicken fillets and cover them with some more tomato sauce - save some tomato sauce.
Next, add the ham slices, cover them with the rest of the tomato sauce, then add the mashed potatoes and cover them with the mozzarella slices. Sprinkle with oregano to taste.
Bake in a preheated oven at 200°C (392°F) for 30 minutes.