Clean mushrooms with a mushroom brush or damp paper towel. Cut half of the mushrooms into slices. Chop the remainder.
Melt half of the butter in a large saucepan and saute sliced mushrooms until golden. Remove and reserve sliced mushrooms. Add remaining butter to the same pan, along with the chopped mushrooms and sweet onions. Sprinkle with salt. Cook, stirring often, until onion is soft.
Return sliced mushrooms to the pan. Add flour and cook, stirring constantly about 2 minutes, until smooth. Slowly add chicken broth while stirring. Simmer, stirring often, until thickened. Add nutmeg and pepper. Taste and adjust seasoning, if need be.
Add heavy cream and bring to a simmer. (Do not boil.) Ladle into soup bowls and garnish with chopped parsley.
Yield: 2 entree servings or 4 smaller appetizer servings