Wash the pork thoroughly then sprinkle with salt and ground black pepper.
Preheat a large skillet over medium-high heat. Melt the butter.
Arrange the pork in the pan. Fry each side for 5-10 minutes, depending on the thickness of the chops.
Take out the pork from heat and set aside.
In the same pan, toss in the onions and saute for a minute. Add the mushrooms then stir. Cover and cook for 2 minutes.
Remove the cover and spread out the spinach over without stirring. Cover again and cook for a minute.
Uncover; return the pork into the pan and slightly stir all together. Cover again and simmer for 5 minutes.
Done. Serve hot or warm.