In a large heavy pot heat 3 tablespoons oil and saute the leeks until tender, a bout 5 to 8 minutes. Reserve 3 large cloves of the garlic. Add the remaining ga rlic and sweet potatoes to the pot and stir to combine. Add enough chicken stoc k or water to barely cover the vegetables. Season with salt and pepper. Bring t o a boil, reduce heat and simmer until the sweet potatoes are very tender about 20 to 30 minutes.

Cut the reserved 3 cloves of garlic into very thin slices. In a small skillet h eat the remaining 2 tablespoons oil and cook the sliced garlic until golden. Tr ansfer garlic chips to paper towels to drain.

In a blender puree the soup, in batches, until smooth and transfer to another p ot. Taste soup and adjust seasoning if necessary. Return soup to a simmer. Ladl e soup into serving bowls and garnish with garlic chips, crumbled feta cheese a nd chives.