Put the spinach in a saucepan. Let thaw slowly over low heat with the lid on. Peel the onion and garlic. Chop finely and sweat in a little oil until translucent. Add the spinach and mix with the cream cheese. Season with salt and pepper.
Whisk the eggs with the milk. Salt lightly. Bake four crispy omelets one after the other in the remaining hot but not browned oil.
Put each on a plate. Cover with the spinach. Fold up the omelets and serve.