Whisk eggs in a bowl with water and salt and pepper. Mix well until the yolks and whites are fully incorporated.
Heat a non-stick skillet to medium-high and quickly swirl butter until foamy. Pour the scrambled eggs and allow to sit for 5 seconds. Then quickly move the egg to distribute and cook evenly.
Grab the skillet's handle from underneath and tilt the pan to slide the omelette down to the lip. Transfer onto a plate by folding the omelette onto itself. Sprinkle chopped parsley on top.
Optional Fillings
For omelettes with fillings, repeat the process above. However, before sliding the omelette onto a plate, sprinkling your desired filling onto the bottom edge and then flip it over onto the plate to close around the filling.