Place milk, cream cheese, flour, and salt in a blender and blend until smooth.  In a non-stick sauce pan, melt butter on med-high heat and add garlic. Let the garlic saute for about 30 seconds, you don't want to burn it.

Then add milk mixture to the pan. Stir constantly for about 3 or 4 minutes or until it just comes to a simmer. Keep stirring and let it cook for a few minutes more. It should be much thicker now.When it's nice and thickened remove the pan from the heat. Add the cheese, stir it up and then cover immediately. Let stand for at least 10 minutes before using. It will continue to thicken upon standing. Season with additional salt if needed.  Also, if you have leftovers in the fridge, the sauce will thicken almost into a solid. Just re-heat and add a little milk and it will be back to normal again.