Bring the milk and water to a boil in a saucepan. Stir in the amaranth and turn the stove down. Add salt and simmer for about 20 minutes.
When the amaranth is cooked, divide the contents of the pan between two bowls. Put 1 tablespoon of butter, 1 tablespoon of Greek yogurt, 1 tablespoon of honey and 1/2 nectarine on top and mix well.