Separate the egg whites into a clean bowl, ensuring no yolk remains.

Whisk the egg whites with water, salt, and black pepper until the mixture is frothy and well-combined.

Heat the olive oil in an 8-inch non-stick skillet over medium-low heat, tilting the pan to coat the bottom.

Pour the egg white mixture into the skillet and let it sit undisturbed for approximately 2 minutes until the base is set and edges pull away slightly.

Distribute the spinach and chives over one half of the omelette.

Carefully fold the other half of the omelette over the filling using a heat-resistant spatula.

Cook for an additional 45 seconds until the center is fully opaque and the spinach is slightly wilted.

Slide the omelette from the skillet onto a plate and serve immediately.