Cook bacon in large skillet over medium-low heat until crisp, about seven minutes. Transfer to paper towels and drain. Crumble bacon and set aside. Reserve 2 tablespoons bacon fat.

Cook potatoes in large pot of boiling salted water until very tender, about 30 minutes. Drain well. Return potatoes to pot; mash. Add buttermilk, butter and reserved bacon fat; mash again. Add chives. Season with salt and pepper. Transfer to large bowl. Top with bacon.