Broccoli Cheese Soup

2 pounds broccoli, cut up
1 large onion, chopped
1/4 cup chicken broth
3/4 cup butter (use milk-free margarine for milk-free)
1 cup flour (use a flour substitute for gluten-free and wheat-free)
4 cup milk (use milk substitute for milk-free)
1/4 teaspoon garlic salt
1/2 pounds grated cheddar cheese (use soy cheese or other cheese substitute -- see substitution page for other ideas -- to make milk-free)

1. Boil broccoli, onion, and broth with just enough water to cover vegetables.
2. When tender, mash mixture with a potato masher.
3. In another pot, while above mixture is boiling, make a thick roux (mixture of butter and flour used to make sauces) with the butter, flour, and garlic salt.
4. Gradually add milk and stir until thickened and smooth (using a whisk on medium heat until not quite a boil). 
5. Combine both mixtures and add cheese.
6. Stir until cheese is melted.