In a saucepan over medium heat, saute the onion in butter for 3-5 minutes until softened.

Add the mushrooms, salt, and pepper. Cook, stirring until the mushrooms release their juices. Add the garlic and thyme and cook for about 1 minute until fragrant.

Pour in the wine to deglaze and loosen any brown bits from the bottom of the pan. Simmer for a few minutes until the wine has almost evaporated.

Add the cream and chicken broth. Simmer for 5 minutes or until reduced by half.

In a small bowl, combine the cornstarch and 2 tablespoons of water or broth and mix well. Add the cornstarch mixture into the sauce a little at a time until the sauce reaches the desired consistency. Depending on your preferences, you may not need all of the cornstarch slurry.

Let the sauce simmer for about 1 minute.

Season with fresh parsley and additional salt and pepper if needed.

Serve and enjoy!