Put the potatoes into a large pot, add the bay leaves, 2 tablespoons salt, and cover with cold water. Bring to a boil over medium-high heat and cook until the potatoes are tender, about 20 minutes. Remove the bay leaves and drain the water from the potatoes, reserving 2 tablespoons cooking water. Smash potatoes in a large mixing bowl. Add the sour cream, butter, horseradish and season well with salt and pepper. Garnish with chopped fresh chives.