See Chicken Stock recipe. Melt the butter in a soup kettle and add onion and garlic. Cook for 5 minutes over moderate heat. Strain a quart of chicken stock into the pan and simmer for 10 minutes. Stir in the bread slices and add bay leaf and thyme. Simmer for 10 minutes longer. Put the mixture into a food processor and process to a puree. Force through a sieve and add cream. Heat through and correct seasoning.