Preheat the oven to 190°C fan.
Place the onion, peppers and garlic in a single layer in a large roasting tin or baking tray. Spray with low-calorie cooking spray and toss well to coat. Place in the oven to roast for 30 minutes, or until tender; turning the vegetables over once or twice during cooking.
Add the mushrooms, courgette and tomatoes and spray again with low-calorie cooking spray. Return to the oven and roast for a further 15-20 minutes or until all the vegetables are soft and browning a little around the edges. Set aside.
Place the yoghurt, cream cheese and Parmesan into a bowl and mix well until completely blended. Stir in the basil leaves and season with salt and freshly ground black pepper, to taste. Set aside.
Place the tagliatelle in a large saucepan of salted boiling water and cook for 8-10 minutes or according to the packet instructions, until 'al dente'. The tagliatelle should be tender to the bite but not too soft. Drain well and return to the saucepan.
Add the roasted vegetables and yoghurt mixture to the tagliatelle in the saucepan and stir until just combined. Taste and season with salt and freshly ground black pepper, if needed. Serve at once.