Remove green leaves from the cauliflower, wash, and place, the cauliflower in cold water, with a little salt added, and simmer for a few minutes. add the cauliflower to a soup pot. Add 1 teaspoon salt to each quart of water. When tender, about 10-15 minutes, remove one half and brake into florets. Continue to cook the remaining cauliflower until mushy.Cool slightly, place in a food processor with some of the water, and run on high speed for 30 seconds or until it has turned to a smooth sauce. In a frying pan saute the onion until glossy, being careful not to brown. Stil in flour, and add the broth and the “sauce” all at once. stir continually while bringing the soup to al boit. Let simmer 10 minutes. Remove from heat. Beat the egg yolk with the cream, a touch of grated nutmeg, and white pepper, and add to the soup in a thin stream, and under constant stirring. Add florets and placesoup pot back on the burner. heat through, but do not let it boil. serve immediately.