In 3-4 quart saucepan over medium heat, melt butter. Add onion, carrot, celery and garlic, and cook, stirring often, until soft but not browned. Mix in pepper, marjoram, nutmeg, potatoes and broth. Bring to a boil, cover, reduce heat slightly, and boil gently until potatoes are tender, 25-30 minutes. Puree soup, about half at a time, in blender or food processor until smooth. Return to cooking pan. Gradually blend in milk and reheat until steaming hot. Do not boil. Stir in cheese, about 1/4 cup at a time, until it is smoothly melted into soup. Taste, and add salt if needed. Serve immediately.