Cream of pumpkin soup

The pumpkin and potatoes are peeled and cut into cubes. Boil them in salted water until tender, then let them cool and mash into a smooth consistency. Return the mixture to the heat and bring to a boil while stirring constantly, then add the hot milk. Stir and, once it boils again, remove from the heat. Finally, add the butter in small pieces. The soup is served garnished with finely chopped green onion and yogurt/sour cream MyDay.