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.