Boil a pot of salted water.
Add the potatoes and cook for approximately 15 minutes, until tender but firm. Drain afterward.
Heat milk and butter in a small saucepan, put into low heat until the butter is melted.
Slowly blend the butter and milk mixture into potatoes using an electric beater. Wait until it is creamy and smooth.
Season with pepper and salt. Server together with the crab cakes.