Heat the Butter and oil in a large pan over a Medium Heat
Add the onion and Garlic and cook for 2 minutes
Add the Mushrooms and cook for 5 minutes until browned on the edges
Add the Cream, continuously stir until the the sauce thickens, around 5-8 minutes
Add the chopped Parsley and stir into the sauce
Take off the heat, season with Salt and Pepper and serve