Crack the eggs into a mixing bowl and whisk with a fork. Add a pinch of salt and pepper.

Wash the spinach and leave wet (this helps to wilt the spinach).

Heat a large frying pan on medium heat, add the spinach to the pan and let it wilt, stirring occasionally.

Remove pan from the heat, rinse the spinach with cold water and squeeze to remove excess water. Chop the spinach finely.

Using the same pan on low heat, add the butter. Add the eggs when the butter is melted and bubbling. Tilt the pan to spread the eggs out evenly. When the omelet starts to cook and firm up, but has not fully cooked on top, sprinkle the spinach over the omelet and grate over the Parmesan.

Using a spatula, lift around the edges of the omelet and then fold it over in half. Remove pan from the heat when omelet is golden brown underneath. Slide omelet on to a plate. Serve hot.