Preheat the oven to 200oC/400oF/Gas mark 6.
Place the aubergine, leeks and red onions into a large roasting tray and drizzle over two tablespoons of the olive oil. Mix well to coat, then roast in the oven for 15 minutes, or until starting to soften.
Add the peppers, tomatoes and herbs to the roasting tin, mix well and season with salt and freshly ground black pepper. Add another tablespoon of olive oil if the mixture looks a little dry. Return the tray to the oven for a further 15 minutes, or until the vegetables are tender and starting to caramelise around the edges.
Meanwhile, bring a large pan of water to the boil. Add the pasta and cook for 10-12 minutes, or until the pasta is al dente. Drain the pasta and return to the pan. Stir in the butter and toss well to coat.
In a small bowl, mix together the parsley, the remaining olive oil and the garlic until well combined.
Remove the roasted vegetables from the oven and tip them into the pan with the pasta, then add the cooked chicken strips. Drizzle over the parsley, olive oil and garlic sauce and mix well.
Stir in the mascarpone cheese until the pasta is coated and the sauce is creamy and smooth. Pile into pasta bowls and serve immediately.