Cannelloni from scratch? Couldn't be easier, as long as you have a piping bag.
Fry half an onion until translucent. Boil and drain 50g frozen spinach.
Add 500g fresh ricotta, 70g of parmesan cheese, the drained spinach and a tablespoon of butter to the cooked onion. Stir to combine over low heat for about a minute.
Make besciamella: melt 60g butter in a pot, add 60g flour, a dash of nutmeg and 500ml heated milk (don't boil) and mix to blend until flour is absorbed.
Make tomato sauce: fry half an onion, add a jar of passata and a third volume again of water, add some finely chopped fresh basil and parsley, a shake of salt and a teaspoon of sugar. Simmer to reduce slightly.
Pipe cheese mixture into instant cannelloni tubes. You cannot force it in with a spoon, by suction, by gravity or any other way. I found out the hard way and then I went out and bought a pack of disposable piping bags for a couple of dollars at Mediterranean Wholesalers*.
Line a baking dish with a smear of besciamella, add the cannelloni tubes, pour over the rest of the besciamella, then pour over tomato sauce. Bake 30-40 minutes in a moderate oven.
*The store's motto 'why pay boutique prices south of the Yarra' is one of the truest advertising lines in existence. It is a no-nonsense place with a huge stock selection, a customer count that includes more Italian grandmothers than Brunswick hipsters, and a cafe serving inexpensive pastries and other treats.