Cook cauliflower in boiling salted water to cover until just tender, drain and save the liquid. In a large pot, melt better over low heat. Add onions and saute until soft and transparent.

Stir in flour, cook for a minute or two, and then blend in chicken broth. Cook over medium-high heat, stirring constantly, until the mixture comes to a boil. Add 1 cup of the reserved cauliflower liquid, the light cream, salt and Worcestershire sauce, then add reserved cauliflower.

Just before serving, heat soup to boiling; remove from heat and stir in grated Cheddar cheese to taste. Ladle into bowls, sprinkling more grated cheese.