- Heat a large heavy casserole dish on medium high heat, then add a good drizzle of olive oil. Brown the chicken on both sides just until golden, then remove chicken from pot and set aside.  
- Lower heat to medium then add pancetta, cook until the fats start to render out, then add onion. Cook until onion is soft, about 5 minutes. 
- Add mushrooms and garlic and cook for further 1 minute. 
- Add the wine and simmer for 1-2 minutes, use a spatula to scrape any brown bits off the pan. 
- Return the chicken to the pot, arranging them in a single layer, then add the chopped tomato. Sprinkle over with sugar and add the rosemary and bay leaf on top.  
- Bring to a boil, then reduce heat to low. Cover pot with lid and leave to simmer for about 15 minutes. 
- Uncover, season with salt and pepper to taste, then increase heat to medium and leave to cook until sauce has thickened, 10-15 minutes. 
- Garnish with chopped parsley and serve with soft polenta or crusty bread.