Wash the mushrooms and remove stumps. Sprinkle with lemon juice to not tarnish. Separately saute onion with chopped stalks. Add salt and pepper. Add chopped ham, garlic and chopped parsley. Confuse well and fill with mushrooms peak, arrange them in a baking dish greased with sunflower oil and bake for 20 minutes in a preheated 200 ° C oven.