1
Heat the oil in a deep, ovenproof sauté pan. Add the onions and fry over a medium heat for 5 minutes until softened, then add the garlic and cook for a minute more.
2
Add the courgettes and mushrooms, increase the heat and fry for about 5 minutes until they are lightly browned. Add the chopped tomatoes and 400ml (1¾ cups) boiling water and season well with salt and pepper. Bring to a simmer and cook for 10 minutes over a medium heat.
3
Preheat the grill to high. Stir the spinach and pasta strips into the pan and, once the spinach has wilted, stir in the basil and two-thirds of the Parmesan and half the mozzarella. Scatter the rest of the cheese over the top and put under the grill for 3–5 minutes until bubbling and oozingly melty.