Sauté the mushrooms and ham

1. Heat up a nonstick skillet over low heat. Add sliced mushrooms to skillet and toast them without oil, undisturbed, for 1-2 minutes or until they start to shrink a little.
2. Add 1/2 tsp butter, diced ham and garlic powder to the mushrooms and stir to combine. Increase heat to medium-low and sauté mushrooms until golden brown. Turn off the heat and set aside.

Make the omelette

1. Separate eggs - put egg yolks in a large bowl and egg whites in a large mixing bowl.
2. Add salt and pepper to the egg whites.
3. Using an electric mixer, beat egg whites until stiff peaks form.
4. Add half the egg whites to the yolks and gently fold to combine using a spatula. Once combined, gently fold in the rest of the egg whites.
5. Heat up 1/2 tsp butter in a large nonstick skillet over medium-low heat. Add egg mixture and spread it out evenly with a spatula. Cover with a lid and let cook for about 5 minutes or until the bottom is golden brown and the top is starting to set. Scatter cheese, sautéed mushrooms and ham on top. Cover and let cook for 1 minute.
6. Turn off the heat and carefully fold omelette over itself, using your spatula. Carefully slide omelette onto serving plate. Top with chopped chives and cracked pepper and serve immediately.