Wash and chop the broccoli and mushrooms. Then peel and chop the onion and garlic. Sweat the onion and mushrooms in 2 tablespoons of olive oil and add the broccoli. Steam everything for about 10 minutes and season with salt and pepper, remove from heat. After everything has cooled down a little, stir in the egg and crème fraîche.
In another saucepan, sauté the garlic in olive oil. Add the cream, mushroom cheese and vegetable stock and season to taste with salt and pepper.
Then fill the cannelloni with the broccoli and mushroom mixture and place in a baking dish. Pour the sauce on top and spread the mozzarella on top. Place in the oven at 180 ° C (top / bottom heat) for about 30 minutes.