Start by heating the oil and frying the sausage meat to brown. Add in the onion, garlic, herbs and pumpkin and continue to cook for 5-6 minutes. In a bowl, mix together the ricotta, grated Parmesan, beaten egg , parsley and season well with salt and pepper. Mix in the cooked sausage and pumpkin mixture. Pour the readymade tomato sauce into the base of a large round oven dish. Fill the partly cooked pasta shells with the filling and place into the dish on top of the sauce. Finish off with extra grated cheese, breadcrumbs and a good drizzle of olive oil. Bake in the oven for 15-20 minutes at 200°C till golden brown.