1. Place 1 yellow onion, cut in half, in the Thermomix and mix for 5 sec/speed 5. Then scrape the sides of the bowl with a spatula.
2. Add 20 grams of olive oil to the Thermomix and cook for 2 min/100°C/speed 1.
3. Add 30 grams of flour to the Thermomix and cook for 2 min/100°C/speed 1.
4. Add 300 grams of button mushrooms to the Thermomix and cook for 3 min/100°C/speed 3.
5. Add 400 grams of water, 1 cube of chicken broth, 150 grams of semi-skimmed milk, 2 pinches of salt (adjust according to taste), and 2 pinches of pepper (adjust according to taste) to the Thermomix. Cook for 10 min/100°C/speed 2.
6. Add 150 grams of heavy cream and 10 fresh parsley leaves to the Thermomix. Mix for 30 sec/speed 4, then gradually increase the speed to 8.
7. Serve immediately or hot.