Melt butter in soup pot over medium heat. Add flour, stirring until smooth to make a smooth paste, or ?roux?. Cook roux for a few minutes, stirring constantly; do not let it turn brown. Add the chicken stock, white wine and a fresh grating of nutmeg. Stir soup to blend ingredients. Bring to a boil, stirring occasionally. When soup boils, add frozen vegetables. Let soup return to boil. Reduce heat and simmer for about 10 minutes. Add salt and pepper to taste, and serve.