Heat a little oil in a large non-stick frying pan. Add the mushrooms and cook over medium–high heat for 4–5 minutes until golden brown. Add tomatoes and cook for 1–2 minutes until just starting to soften. Stir through basil, salt and pepper. Remove, cover and keep warm. Wipe out the pan.
Whisk together the eggs, parsley, salt and pepper. Heat a little extra oil in the same pan. Add the egg mixture and swirl around the pan using a spatula to move gently until the omelette is just set.
Lay the provolone over half the omelette, cook for a minute then fold the other half over. Cook for another 1–2 minutes, then transfer to a serving plate and spoon over mushroom mix. Serve immediately