Grandma Stahle's Cream of Broccoli Soup

2 large stems of broccoli
1 lg. onion
4 T. salt
1 square butter
3/4 c. flour
2 qts. milk
1 qt. 1/2 & 1/2
salt and pepper to taste

Chop broccoli and onion into small pieces. Place in pan with boiling salt water. Cook until tender. Drain about 1/2 of water and save the water. Leave rest in pan and add 1/2 & 1/2. In large frying pan, make a roux with the flour and butter. Stir until smooth. Add drained salt water and milk. Stir until thick. Add to broccoli and simmer for a while.