Add the leek, onion, garlic, and peppers and continue to cook stirring occasionally, until the onion is translucent (about 3-4 minutes).
Let it come to a boil, reduce heat and simmer until the potatoes are fork tender, about 30 minutes (it will depend on the size of the diced potatoes).
Add the nutmeg, paprika, salt, and pepper and return to heat. Cook whisking constantly until it starts to thicken.
When the soup is ready, add the olive oil béchamel sauce to the pot, stir well and cook for 5 more minutes. Taste, adjust the salt, and serve with chopped chives.