Mushroom Bisque

1 pound fresh mushrooms
1 qt. chicken broth
1 small onion, chopped
7 tablespoons butter
6 tablespoons flour
3 cups milk
1 cup heavy cream
1 tsp. salt
1/2 tsp. pepper
2 tablespoons sherry

Finely chop mushrooms. In a sauce pan, put broth, onions and mushrooms. Simmer for 30 minutes. In another saucepan, melt butter and add flour. Stir until blended. In microwave, bring milk and heavy cream to a boil. Add all at once to butter/flour mixture and whisk until smooth. Add to mushrooms and onions. Add spices and simmer until thick. Add sherry just before serving.