Boil ready made cannelloni tubes in boiling water with the salt and oil for 7-8 minutes or till done.Read the packet instructions.
To prepare the stuffing, heat oil, add the onion and garlic, fry till onion is soft.Add the bell peppers ,corn and spinach and saute for 2-3 minutes.Add the crumbled cottage cheese, herbs,tomato puree, salt and pepper.Cook till the mixture is dry.
To prepare the tomato sauce,heat oil ,add garlic,fry till light brown.Add onion and fry till transparent.Add all the other ingredients and boil till slightly thick pouring consistency(not dry)
To prepare the bechamel sauce heat butter, add the flour and cook till it has a light brown tinge.Reduce heat and add milk stirring continuously so that no lumps are formed.Add seasonings and cook till the sauce starts coating the back of the spoon.Remove from heat,add cheese and mix well.
Stuff cannelloni tubes with the prepared stuffing.
To assemble, spread some tomato sauce at the base of the baking dish.Arrange the stuffed cannelloni on it in a single layer.Spread rest of the tomato sauce on it.Then spread the bechamel sauce on it to cover completely.
Top it up with grated mozzarella cheese and bake at 180 deg C for 20 mins or till cheese is golden in colour.