Melt the butter and olive oil in a skillet over medium heat.
Add the mushrooms and cook them until browned, stirring several times, for around 5 - 7 minutes.
Add the garlic, heavy cream, cream cheese, parmesan, onion powder, and oregano to the skillet and cook for another 5 - 10 minutes, until the sauce is thick and creamy.
Salt and pepper the mushrooms to taste.
Garnish with fresh parsley and serve.
Notes
You can use any variety of whole mushrooms for this recipe. Readers have also noted that they used sliced mushrooms as well