Heat your olive oil on a medium heat in a large sauté pan. Add your onion and cook for about 5 mins until soft.. Add your red peppers and fry for another 5 mins, until all soft and starting to caramelise. Throw in your garlic and cook out for another minute.
Add your sausage meat to the pan and turn up the heat. Fry for 5 mins until cooked and golden, breaking it up with your wooden spoon as it cooks.
Throw in your spinach and cook for 2 mins until wilted and all the moisture has evaporated. Add your Italian herb mix, salt and pepper and stir to combine. Set aside.
Heat your olive oil in a wide saucepan. Add your garlic and chilli flakes and fry for 1 min until fragrant and aromatic. Pop your cherry tomatoes in the pan and simmer for 5 mins, breaking up with your spoon as it cooks down. Pour in your passata and add your sugar. Bring to a boil, then simmer for 15 mins until thick and flavoursome.
Add your double cream and simmer for 5 mins until the sauce has a thick, velvety texture. Add your parmesan, salt and pepper and and stir to combine.
Heat your oven to 200°C.
Using a teaspoon, fill your pasta shells with your sausage mix.
Pour your sauce into a rectangular baking dish. Place your shells in the sauce and top with cheese. Bake for 20 mins, then grill for 5.