Place a large saucepan on the stove over a medium heat. Add the butter, and when melted, add shallots, leeks and garlic and using a wooden spoon to occasionally stir. Cook until leeks are tender, about 7 minutes.
Add the potato, parsnips and apples and cook until just potatoes are starting to soften, about 5 minutes.
Add the broth and apple juice; reduce stove temperature to a simmer. Cover the saucepan and cook until the vegetables are very soft, about 30 minutes.
Remove the saucepan from the heat, add the parsley and using a blender, or an immersion blender, thoroughly purée the mixture.
Return the saucepan to the stove over a medium-low heat and stir in the milk. Heat the soup, stirring occasionally, until the soup is heated through and boils. Taste and season with salt and pepper.
Tasted and perfected in the Sur La Table kitchen.