Heat oil in a large 25cm non-stick frying pan over medium-high heat. Add the mushrooms, season with salt and pepper and cook for 6-7 minutes or until golden. Remove, cover and keep warm. Wipe out the pan.

Separate eggs, placing egg yolks into a small bowl and egg whites into a large bowl. Add milk to egg yolks and whisk with a fork. Using a hand beater, whisk egg whites and the ¼ teaspoon salt until stiff peaks form.

Heat the frying pan over medium heat. Brush with butter to grease. Using a large metal spoon, gently fold the egg yolks into the egg whites.

Pour half the mixture into the pan and cook for 4-5 minutes, or until golden and the eggs are just set. Spoon over half the crème fraiche, parmesan and mushrooms and carefully fold the omelette in half. Cook for 1 minute or until almost set.

Transfer to a serving plate (omelette will continue cooking once removed from heat). Repeat using remaining eggs, crème fraiche, cheese and mushrooms. Sprinkle with chives, extra parmesan and pepper to serve.