Mashed Potato Soup

Ingredients (8)

• 1 tablespoon chopped onion
• 1 tablespoon butter
• 2 cups milk
• 1-1/2 cups mashed potatoes (prepared with milk and butter)
• 1/2 teaspoon salt, optional
• 1/8 teaspoon celery salt, optional
• 1/8 teaspoon pepper
• 1 tablespoon minced chives