Wash mushrooms quickly and pat dry. Slice them evenly. Do not soak them in water. Mushrooms absorb water easily. Dry mushrooms brown better and give richer flavor.

Heat butter and olive oil in a large pot over medium heat. Add chopped onion. Cook until soft and light golden. Add garlic and cook for one minute. Stir gently to prevent burning.

Add sliced mushrooms into the pot. Stir well so they coat in butter. Cook for about 10 minutes. Mushrooms will release water first. Continue cooking until liquid reduces and mushrooms brown slightly.

Sprinkle fresh thyme, salt and black pepper over mushrooms. Stir gently. Herbs add warm French flavor. Let them cook together for two minutes to blend flavors nicely.

Add vegetable or chicken stock slowly. Stir and scrape the bottom of the pot. Bring the soup to a gentle boil. Then reduce heat and simmer for 15 minutes.

For a smooth soup, use a blender carefully. Blend until creamy. If you prefer texture, blend only half. Return blended soup to the pot safely.

Pour in heavy cream slowly. Stir gently. Let it simmer for five more minutes. Do not boil after adding cream. Taste and adjust seasoning if needed.

Ladle the soup into bowls. Garnish with fresh parsley. Serve hot with crusty bread. The warmth and aroma feel comforting and elegant.