Quarter the mushrooms and chop the onion. Fry the strips in oil, remove from the pan and set aside.
Then fry the onion cubes together with the mushrooms. Deglaze with a dash of milk and simmer briefly on medium heat.
Add the spaetzle and sliced meat, as well as milk and cream. Swirl through, simmer and simmer on a lower level with the lid closed for about 10 minutes, until everything is nice and creamy.
Salt and pepper to taste. Finally sprinkle some chives over the top, then serve.