Pre-heat the oven to 350°F.
Arrange the bacon on a sheet pan and bake for 12-15 minutes until crisp. Cool and chop.
Put the potatoes in a medium size saucepot and cover with cold water. Bring the water to a boil and season with salt. Cook until tender, about 15 minutes. Drain and mash the potatoes with buttermilk and season with salt and pepper. Stir in the chives and cheddar, then fold in the bacon.