Wipe the mushrooms clean and slice them.
Dice the onion and sauté it in oil or butter until translucent. Then add the crushed garlic.
Add the mushrooms and cook for 6 to 8 minutes until they release their liquid and become slightly golden.
Sprinkle with flour (if using), stir well, then pour in the broth.
Season with salt, pepper, and thyme. Cook for 10 to 15 minutes.
Add the cream, bring to a boil, then optionally blend with an immersion blender, or leave it chunky.
When serving, sprinkle with fresh parsley.