1) In a large pot over a medium flame, sauté the leeks, onions, ginger, garlic, nutmeg, a pinch of kosher salt, a pinch of black pepper, and the olive oil. Keep pot uncovered, lightly stir, and sauté until the onions and leeks begin to lightly brown. 2) Toss in the apples, parsnips, sweet potatoes, and yukon gold potato. Gently stir root vegetables with the onions and leeks. 3) Add 4 cups of water to the pot, or enough water to just cover all the vegetables. Return lid to pot, bring flame to a high until soup begins to boil. Return flame to medium-low , and let the soup boil for 20-25 minutes. 4) Take the soup off the flame and with an immersion blender, blend the soup well, removing any chunks. 5) Add salt and pepper to taste. Soup keeps up to five days in the refrigerator, and freezes very well.