| 1 | Melt butter in heavy large saucepan over medium heat. |
| 2 | Add mushrooms and saute until soft, about 4 minutes. |
| 3 | Add flour and stir for 2 minutes. |
| 4 | Slowly mix in half and half. |
| 5 | Simmer until thickened, stirring frequently, about 4 minutes. |
| 6 | Combine yolk and lemon juice in small bowl. |
| 7 | Gradually whisk in half of soup. |
| 8 | Return to saucepan and stir until heated through; do not boil. |
| 9 | Season generously with salt and pepper. |
| 10 | Serves Recipe from "too busy to cook", bon appetit, december, 1989 |
