I came across this recipe a few weeks ago in Healthy Helpings by Norene Gilletz. I altered it slightly and have been making it several times since as it is so easy and quick.
2 tbsp butter
3 tbsp flour
11/2 cup skim milk
1 bay leaf
grated cheese of your choice
salt and pepper to taste
Combine butter and flour in a glass measuring cup. Microwave on high for 30 seconds. Gradually add in milk. Add bay leaf.
Microwave on high 3 to 31/2 minutes, until bubbling, whisking about every 30 second. Discard bay leaf and add cheese according to your taste (the recipe suggests 1/3 cup). Season to taste.
This is a fine sauce to use for macaroni cheese, lasagne, vegetables or fish.