Place well-washed spinach in a saucepan with a half cup of water and cook it over high heat until it is completely wilted.  Drain the spinach and, when it is cool enough to handle, squeeze it into a ball between your hands until all the liquid is removed.
Mince the spinach and place it in the top part of a blender.  Add a little milk and puree until the mixture is completely smooth.  Add the remaining milk and the rest of the ingredients except the melted butter and blend at high speed.
Pour the mixture into a bowl, add the melted butter and let the batter rest for 2 hours.
Brush the surface of a crepe pan with  a little melted butter.  Place the pan over medium to high heat and allow it to heat.  Add a spoonful of batter, just enough to coat the bottom of the pan thinly.  Pour out any excess batter.
Cook the crepe for 1 or 2 minutes, then loosen it with a sharp knife.  Turn it over with your fingers or a spatula and lightly brown the other side.  After the first crepe reduce the heat to medium.  Slide finished crepes onto a plate.