Vichyssoise (Chilled Potato and Leek Soup)

1 onion
med diced
2 Tbsp butter
1 Tbsp olive oil
6 leeks leeks
thoroughly rinsed and sliced (white and light green parts only)
3 large potatoes
peeled and med diced
1 qt chicken broth
Salt and pepper to taste
Pinch of nutmeg
1 C heavy cream
Chill your serving vessels in advance by putting them in the refrigerator or freezer.
For the soup
In a large stock pot, heat the olive oil and the butter, over medium high heat. Sauté the onion until translucent (about 2 minutes). Add the leeks and sauté until soft (about 4-5 min).
Add the potatoes and sauté with the onions and leeks for a couple of minutes. Add a small pinch of nutmeg and season with salt and pepper. Add the chicken broth and bring to a boil. Once it starts boiling, lower the heat and simmer for 30 minutes, or until the potatoes are tender.
Using an immersion hand blender, puree the soup until smooth. Alternatively, you can work in batches using a regular blender and pour it back into the stock pot. If you like your soup to be extra smooth, you can pass it through a fine mesh sieve too.
Add the heavy cream and turn the heat back up to medium. Cook for about 5 minutes so it thickens a little. Taste for seasoning and add more salt and pepper if necessary. Add a pinch of freshly grated nutmeg. Remove from heat.
Wait for the soup to cool down to room temperature and chill for at least one hour before serving.
To Serve
Garnish with some chopped chives and serve.