Toss cubed butternut squash with olive oil and salt. Roast for 30 minutes until soft and starting to caramelize.
While the butternut roasts, saute the onion and garlic until soft and translucent.
Add the baby spinach and cook until wilted down then season with nutmeg, salt and pepper.
Transfer to a bowl and mash with the butternut. Allow to cool to room temperature then stir in the mascarpone, grated parmesan and sage. Taste and adjust seasoning if necessary.
Stir together the tomato passata/tomato puree, oregano, sugar and salt. Transfer half of the sauce to a suitable baking dish and spread out.
Transfer the filling to a piping bag then snip off the end and fill each cannelloni and place in the baking dish on top of the tomato sauce. Once the dish is full, top with the remaining tomato sauce and the grated mozzarella and parmesan cheese.
Cover the dish with foil and lace in the oven and allow to bake for 30 minutes until the pasta is cooked. Remove the foil and cook for another 15 minutes until golden brown. Remove from the oven and allow to rest for 5 minutes before serving. I topped my cannelloni with fried sage but that's optional.