01 - Heat butter in a large skillet over medium heat until melted and foaming.
02 - Add finely chopped shallot and sauté for 2 minutes until softened.
03 - Add minced garlic and cook for 30 seconds until fragrant.
04 - Stir in sliced mushrooms and cook for 5 to 7 minutes, stirring occasionally, until golden and liquid evaporates.
05 - Pour in dry white wine, if using, and let simmer for 2 to 3 minutes until mostly reduced.
06 - Add vegetable or chicken stock and fresh or dried thyme, then simmer for 3 to 4 minutes to blend flavors.
07 - Reduce heat to low, stir in heavy cream, and cook gently for 2 to 3 minutes, stirring often, until sauce thickens.
08 - Season with salt and freshly ground black pepper to taste. Remove from heat and garnish with chopped parsley if desired.