Put all the peppers in a large frying pan over a medium heat with a little olive oil and a pinch of salt and pepper. Place a lid on, and cook slowly for 15 minutes until softened. Don’t rush this too much, as cooking the peppers slowly like this really helps to bring out the flavour. Add the onion and cook for a further 20 minutes. Then add the garlic and parsley stalks and toss around, keeping everything moving in the pan. Cook for about 3 minutes more. Have a little taste, and season with a bit more salt and pepper. Add the vinegar – it will sizzle away, so give everything a good toss. Then add one handful of the grated Parmesan and the mascarpone or crème fraîche if you are using it and turn the heat down to minimum while you cook the pasta.