01 - Melt butter in a large skillet over medium heat. Add finely chopped shallot and sauté for 2 minutes until translucent.
02 - Incorporate minced garlic and cook for 30 seconds until fragrant.
03 - Add sliced mushrooms, stirring occasionally, until they are browned and softened, about 6 to 8 minutes.
04 - Pour in dry white wine and cook for 2 to 3 minutes, scraping the skillet to lift browned bits, until the wine has reduced by half.
05 - Add vegetable or chicken stock, sea salt, black pepper, and thyme. Simmer gently for 5 minutes to allow slight reduction.
06 - Stir in heavy cream and, if using, crème fraîche. Continue simmering for 3 to 4 minutes until the sauce thickens.
07 - Remove from heat, mix in chopped parsley, and adjust seasoning as necessary. Serve warm with your choice of main dish, garnished with additional parsley.