2 tablespoons unsalted butter
1/2 cup minced shallots
3/4 pound broccoli, chopped coarse (about 3 1/2 cups)
2 cups chicken broth
1 cup water
1/2 cup heavy cream
1 1/2 teaspoons fresh lemon juice, or to taste
Salt and ground black pepper.
In a heavy saucepan cook the shallots in the butter over moderate heat, stirring, until soft about 8-10 minutes. Add the broccoli, the broth, and the water, and simmer the mixture, covered, for 15 to 20 minutes, or until the broccoli is very tender.
In a blender, purée the soup in batches until it is smooth, transferring it as it is puréed to another heavy saucepan. Whisk in heavy cream and lemon juice and salt and pepper to taste, heat the soup over moderately low heat until hot, about 3 minutes. Do not let the soup boil.
Serve immediately.
Adapted from Cooks Illustrated Soups & Stews