In a large pan cook the potatoes until soft.
Let them cool down for a bit.
Once the potatoes are warm enough to hold them, peel them off and chop them into smaller pieces.
Smash them up with a smasher and set aside.
Preheat the oven to 400ºF {200ºC} and line a muffin pan with cupcake liners or muffin tins.
In a small pan, heat milk and butter until they are about to boil, and add in the mashed potatoes, cheese, onions, nutmeg, salt, and pepper. Mix well.
Incorporate the yolks and mix well.
In a stand mixer beat the egg whites until hard peaks are formed.
Start mixing one big spoon at a time with soft movements until you get all the egg whites and potatoes mixed.
Divide evenly the mixture for 12 cups and bake for about 15 to 20 minutes or until it rises and is golden brown.
Serve immediately as your side dish, or with salad. It also goes perfectly with sausages and ketchup for kids!
This recipe can take about an hour or so if you prepare the mashed potatoes the same day. If you have it done or have some leftover mashed potatoes then it might take no more than 30 minutes!