Peel Potato (400 gram) and cut into 1/2-inch cubes.
Fill a pot with Water (1 liter) and bring to a boil. When it comes to a boil, heavily salt the water and add the potatoes. Cook until soft.
Drain Potatoes and then press them through a fine-mesh sieve to remove any lumps. Pureeing through a sieve will help your potatoes to have a smoother consistency.
In a small saucepan on medium-low heat the Milk (125 milliliter) and add half the Butter (125 gram). Once simmering and butter has melted, remove from heat.
In a medium saucepan heat the sieved potatoes over medium-low heat. Add half of the warm milk butter mixture, and fold the potatoes and milk together until combined. Add in remaining Butter (125 gram) and continue to stir gently. Once the butter has melted, pour in the rest of your milk and stir until just combined.
Remove Potatoes from heat and season with Salt and Pepper (to taste). Top with more butter if desired. Serve hot.