Splash a few tablespoons of olive oil into the pot and add the onions, celery, carrot and capsicum and saute on medium heat for 5 minutes, or until onions are translucent.
Add the chicken pieces, chorizo and garlic. Season with salt and pepper and cook, stirring every now and then, until chicken is browned.
Add the mushrooms, oregano, chilli, paprika and fennel seed and cook for a further 1 – 2 minutes, or until mushrooms start to soften.
Add the tinned tomatoes, passata and water and stir to combine. Season with a little salt and pepper and bring to the boil. Reduce heat and simmer, stirring every now and then, for 30 minutes.
When the sauce is almost done, cook the casarecce in a large pot of boiling salted water. Drain and add straight into the pot of sauce. Stir to combine the pasta and sauce then remove from the heat and serve with grated parmesan and crusty bread.