Wash the spinach in cold water unless it is pre-washed.
Even if it is you might still want to give it another rinse!
Fry the onion and garlic in the butter or oil for a few minutes, if using.
Add the spinach to the pot and put the lid on.
If you are not using onion and garlic, add a little water or oil to the pan.
Turn the heat quite low and just let the spinach cook down.
You can stir it occasionally if you wish.
Once it has wilted, you can stir in the cream cheese and also add salt and pepper to taste.
A pinch of nutmeg is also nice.