1. In large heavy soup pot, melt butter over medium heat.
2. Sauté mushrooms for 5-6 minutes or until mixture from mushrooms has evaporated.
3. Sprinkle flour over mushrooms and cook 1 minute. Gradually stir in broth.
4. Bring to boil, stirring constantly. Add thyme and bay leaf.
5. Reduce heat and cover. Simmer 15- 20 minutes. Remove bay leaf.
6. In small bowl whisk egg yolks with cream; stir 1 cup (250 mL) hot broth into cream mixture and then return all to saucepan.
7. Heat over low heat (do not boil) until hot about 5 minutes.
8. Add pepper to taste. Serve sprinkled with parsley.