Cut the potatoes into 1-inch cubes and place them in a large pot with the chicken broth. Add enough water to cover the potatoes and add about 2 tablespoons of salt. Bring to a boil, then lower the heat and simmer, uncovered, for about 10 to 12 minutes, until the potatoes fall apart easily when pierced with a fork.
Meanwhile, heat the milk and butter in a small saucepan, until the butter is melted. Keep warm.
As soon as the potatoes are tender, drain in a colander.
Place hot potatoes in mixing bowl and mix until smooth, about 1 minute.
Slowly add in milk/butter mixture and sour cream.
Turn up speed and beat for about 30 seconds, or until milk is absorbed. Gradually turn up speed and mix for
1 minute longer.
Switch to whipping attachment and beat for about 1 minute, or until fluffy.
Serve warm topped with extra butter (if desired) and chopped chives.
