Potato and Leek Soup

1/4 cup butter
1 whole leek, chopped
3 medium onions, chopped
1 ½ pounds potatoes, cubed
½ cup oats
2 cloves garlic, crushed
2 cups chicken stock
2 cups milk
salt and pepper to taste
fresh chives, chopped (for garnish)

Melt butter in a large pan. Saute onions and leek until tender. Add potatoes. Cook until potatoes are golden brown. Add oats and garlic. Cook one more minute. Reduce heat to low. Stir in chicken stock and milk. Simmer 30 minutes, or until vegetables are tender and soup thickens. Season to taste with salt and pepper. Serve garnished with chopped chives.