Heat olive oil in a pan and braise both in it. Add the tomato puree and stock and simmer gently for about 15 minutes. Add the cream and herbs and season with salt and pepper.
In the meantime, drain the tuna, clean and finely dice the mushrooms and mix with the fish. Pour the mixture into the cannelloni.
Pour enough of the sauce into a flat dish to cover the base well. Put the cannelloni on top and pour the rest of the sauce over them.
Bake in a preheated oven to 180 degrees for about 20 minutes, then pour the cheese over it and continue to bake until the cheese is golden yellow.