1.Remove the stems from the mushroom and chop them. Set them aside for later use.
2.Wash and clean the insides of the mushroom and dry them over a kitchen towel.
3.Heat the olive oil on medium heat in a pan and saute the onion and garlic for 2 to 3 minutes.
4.Roughly ground the Italian sausage and add it to the pan along with the reserved chopped mushroom stems. Cook for 8 to 10 minutes or until halfway cooked,
5.Add oregano salt and pepper and saute for a minute.
6.Let the mixture cool at room temperature.
7.In the meantime, preheat the oven to 350 F and prepare a baking tray by lining it with parchment paper.
8.Mix sausage mixture with cream cheese and parmesan cheese in a mixing bowl.
9.Now, fill the mushrooms with the filling and place them over the baking tray.
10.Top the mushrooms with the cheddar cheese,
11.Bake the mushrooms for 15 to 20 minutes.
12.Serve hot with a sprinkle of parsley on top.