Clean the mushrooms with a damp paper towel to remove any dirt or debris. Trim the ends of the stems if desired.
Heat the butter and extra virgin olive oil in a large pan or skillet over medium-high heat. Add the onion and sauté until tender, about 3 minutes.
Add the mushrooms and cook for about 4 to 5 minutes, until golden brown around edges.
Splash in the dry white wine, scraping any browned bits from the bottom of the pan. Cook for 2 minutes, or until pan juices are reduced slightly.
Add the garlic and 1 tbsp of the parsley to the pan and stir about 30 seconds, until fragrant. Season with salt and pepper to taste. Add a pinch of red pepper flakes and stir. Garnish with the remaining parsley and serve warm. Enjoy!
* You can use a good quality white wine or chicken broth or vegetable broth to deglaze the pan.