Peel and quarter the potatoes, cover them with water and bring to the boil on high heat. Lower the heat and simmer, covered, for 20–25 minutes, or until tender. Drain, then shake the pan for a minute or two on low heat to dry the potatoes.
Beat the potatoes in a medium bowl with an electric mixer on low until they are almost smooth. Add the milk, butter, salt, paprika and pepper and beat the mixture until light and fluffy. Cover the bowl and refrigerate for at least 1 hour.
Lightly beat the egg, then stir it with the spring onions into the potato mixture until well mixed. Heat the oil in a large frying pan on medium heat. Spoon half of the potato mixture into four mounds in the pan and flatten the tops slightly.
Cook, turning once carefully, for about 4–5 minutes on each side, or until they are browned. Remove from the frying pan, cover and keep warm.
Make four more pancakes in the same way with the remaining potato mixture, adding more oil, if necessary.