Preheat oven to 220°C (200°C fan-forced).
Cut tomatoes in half, place on a roasting tray, drizzle with oil, sprinkle with salt and roast for 45 minutes.
Fry sausages in a little oil until nicely browned and cooked through. Remove and set aside. Keep frying pan and juices for later.
Slice peppers in half. Remove stem at top and clean out seeds and excess white parts from the inside. Slice peppers lengthways into strips.
Using the sausage pan and its oil, fry peppers along with garlic and crushed fennel for 15 minutes until starting to collapse and gain colour. Season with salt as frying.
Remove tomatoes from oven and transfer to a blender. Add chicken stock and blend until smooth.
Pour sauce over peppers, bring to the boil then cover and turn to simmer. Let the tomato pepper sauce slowly cooking down for 25 - 30 minutes until peppers are soft and juicy.
Cut sausages in half lengthways and add to the tomato peppers sauce. Keep on a very low leat to warm the sausages into the sauce but not over-cook them. Taste and season with salt and pepper as necessary.
Prepare polenta. Bring chicken stock to the boil and gently whisk in polenta. Turn to medium-low heat and continue to stir every minute or so until smooth and creamy, approx 10 minutes. Remove from heat, stir through butter, add parmesan, and season with salt and pepper.
Divide polenta between bowls. Top with sausage ragu. Drizzle with olive oil and sprinkle with parmesan.