Potato soup from Norway

This recipe could be included in a Norwegian lunch menu.

1. Put potatoes, onion, and salt in a heavy 2-quart saucepan. Cover with water and bring to a boil.
2. Lower the heat and simmer until the potatoes are soft, 15-20 minutes. Mash potatoes and onion in the same pan, with the remaining liquid.
3. Return to the heat and add milk, slowly, stirring continuously then add butter, parsley, salt and pepper. Let it simmer until the soup is well blended and smooth.