Broccoli Cheddar Soup

For posterity.  And Aunt LoLo who has lost this recipe each of the four times I've sent it to her over the years.  *mwah*  I believe this originated with my mother-in-law's little sister.

Before you start, have cooked broccoli on hand, and 1 cup of broccoli cooking water.  How much?  Up to you.  1/2 a Costco bag is good for a big pot of this.

In a large pot, melt 1/4 cup butter and saute 2/3 cup chopped onion.  (An onion.  Chop an onion.  Or two.  I really like onions)

Add 1/2 cup flour and whisk well to make a white roux. 
Add 2 cups chicken broth, 1 cup broccoli water, 4 cups dairy (could be half cream, I use all milk), 1/2 tsp Worchestershire sauce, 3/4 tsp salt (taste first!!).  Mix all together, add broccoli and heat.  Add 1 cup grated sharp cheddar cheese, or more to taste. 

Don't let this boil, or it will curdle.