Heat a pan or cast iron over high heat and add butter. When butter begins to sizzle, add mushrooms and cook, stirring, until browned, 6 to 8 minutes.
Add thyme and garlic, and stir. Make sure to not let the garlic burn. and add more butter as needed.
Add salt, pepper and rd pepper flake and continue to sauté for a minute more, then add red wine.
Add crème fraiche and let simmer for 2 minutes.
Meanwhile, toast and butter bread.
Spoon mushrooms and sauce over toasted bread. Top with parsley or chives.