Clean and slice 500 g mushrooms
Finely chop 1 onion and 2 garlic cloves
Melt 2 tbsp butter in a pot over medium heat
Add onion and cook until soft
Add garlic and cook for 1 minute
Add mushrooms and cook until browned and reduced
Sprinkle in 2 tbsp flour and stir well
Cook for 1 to 2 minutes
Slowly pour in 4 cups vegetable or chicken stock while stirring
Bring to a boil, then reduce to a simmer
Cook for 10 to 15 minutes
Add 1 cup heavy cream
Season with salt and black pepper
Blend partially or fully if desired
Heat gently for 2 to 3 minutes
Serve hot with parsley or croutons if desired