Peel, wash, and cut the potatoes into very small cubes. Place them in a skillet with a splash of oil over medium heat. Add the chopped onion (if using) and a good pinch of salt (adjust to taste as you go).

Stir with a spoon for about 10 minutes over medium-low heat. When the potatoes are soft, use the spoon to mash them a bit. (You can leave them whole if you prefer, but I like to mash them for a quicker cook and a better texture.)

While mashing, cook for about 5 more minutes until it’s almost like mashed potatoes. Turn off the heat and let it cool slightly.

In a bowl, crack the eggs and add a good pinch of salt to each. Mix well. When the potatoes have cooled and are no longer hot (so the eggs don’t cook), add them to the bowl and mix together.

In a deeper skillet, add a small splash of oil over low heat. Pour in a little more than half of the potato-egg mixture (about two-thirds) and spread it evenly across the pan. Now add the filling—typically cheese and ham.

Place 4 slices of cheese and 4 slices of ham, then top with the remaining 4 slices of cheese. Pour the rest of the potato-egg mixture over the top and spread it with a spoon to cover the cheese. Cook for 7–8 minutes.

After that time, carefully flip the omelette using a large plate. Place the plate over the skillet, hold the skillet with one hand and the plate with the other, and quickly flip it over. The omelette will slide back into the skillet to cook the other side. Use a spoon to shape the edges so it’s nice and round. Cook for another 7 minutes.

Remove from the skillet with the help of a plate. It’s irresistible—you’ll want to eat it right away!