1/4 c. butter
1 med. onion, chopped
1/4 c. flour
3 c. chicken broth
3 c. milk
4 c. shredded Cheddar cheese

In 3 quart saucepan over medium-high heat, in hot butter, cook onion until tender, about 5 minutes. Stir in flour and cook until flour has blended with onion mixture.

Add chicken broth; cook, stirring constantly until mixture is slightly thickened. Add milk and heat just to boiling, stirring constantly.

In covered blender container at medium speed, blend about 1/4 of milk mixture at a time until smooth. Return to saucepan and, over medium heat, heat just until boiling, remove from heat.

With wire whisk or slotted spoon, stir in cheese until melted. If cheese does not melt completely, cook over very low heat, about 1 minute, stirring constantly.