Peel and chop the onion. Peel and slice the mushrooms. Set aside 100 g.
In a saucepan, melt 20 g of butter over medium-low heat. Add the onion and sweat for 3 min.
Add 400 g of mushrooms and cook for 2 minutes over high heat, stirring.
Dissolve the stock cube in 1 litre boiling water. Bring to a simmer and cook for 20 minutes over medium-low heat.
Meanwhile, brown the reserved mushrooms in a frying pan over medium heat with the remaining butter.
Add the crème fraîche to the pan, heat gently for a minute then blend using a hand blender. Add the SAINT AGUR® Blue Crème and blend.
Pour the soup into bowls or deep plates. Add the fried mushrooms, a few sprigs of parsley and enjoy hot!