Mist a large nonstick frying pan with cooking spray and set over a medium to high heat. Cook the onion, stirring, for 5 minutes or until softened. Add the garlic and all the mushrooms and cook, stirring, for 5 minutes until the mushrooms are golden. Add the spinach and cook for 1 minute until wilted. Remove the pan from the heat, season to taste and set aside.

Whisk together the eggs, milk and chopped parsley in a large jug until combined, then season well. Lightly mist a small nonstick frying pan with cooking spray and set over a medium to high heat. Pour the egg mixture into the pan and cook for 30 seconds or until the base is set. Using a spatula, draw the edges of the omelette into the center to allow the uncooked egg mixture to run underneath. Cook for a further 3 minutes or until almost set.

Spoon the mushroom mixture over half the omelette and then scatter over the ricotta. Fold the omelette over to enclose the filling.

Slide the omelette onto a plate and serve topped with extra parsley leaves and the Parmesan.