Wash and clean the mushrooms, zucchini, tomatoes, onion and garlic. Halve the zucchini and scoop out with a spoon.
Cut the onions, garlic, mushrooms and tomatoes into small cubes and season with the parsley, herbs and salt and pepper.
Mix the filling with the parmesan and fill the zucchini with it. Place in a baking dish.
Bake in the oven preheated to 200 ° C for approx. 30 - 40 minutes on the middle shelf.
For the sauce, heat the oil in a saucepan, add the chopped onion and the chopped zucchini pulp to the saucepan and sauté. Sprinkle the flour on top and pour the broth on top. Let the sauce simmer for 2-3 minutes while stirring, then stir in the sour cream.