4 lbs russet potatoes peeled and cut into 1” pieces 1½ cups whole milk 8 tbsp unsalted butter cut into pieces 2 tsp salt ½ tsp pepper
Put potatoes in colander and rinse under cold running water for 1 minute or until it runs clear. Drain potatoes. Fill dutch oven with 1” water and bring to boil. Place steamer basket in dutch oven and fill with potatoes. Reduce heat to medium and cook covered until tender, 20 to 25 minutes.
Heat milk, butter, salt and pepper in small sauce pan over medium heat. Whisk until smooth, about 3 minutes. Cover and keep warm.
Pour contents of dutch oven into colander and return potatoes to dry pot. Stir over low heat until potatoes are thoroughly dry, about 1 minute. Using stand mixer w/ whisk, break potatoes into small pieces on low speed (30 seconds). Add milk in steady stream until incorporated. Increase speed to high and whip until potatoes are light and fluffy and no lumps remain, about 2 minutes.