Wash and dry the chicken fillet. Cut into thin slices with a sharp knife.
Grease a hot pan with olive oil. Put the chicken slices in the pan, salt and pepper. Fry over high heat for 2 minutes until the breast is browned on one side. Turn the breast on the other side and fry for another 2 minutes. Then transfer to a plate.
Add more olive oil to the pan, then add the mushroom slices and chopped onion. Fry for 5 minutes, stirring. Salt.
Pour cream and broth into the pan. Bring to a boil.
Transfer the fried breast slices to the pan. Stir and simmer on low heat under the lid for 15 minutes. Make sure the liquid doesn't boil away. If it is not enough, pour in more broth or cream.