Preheat oven to 375 degrees Fahrenheit.
Wash potatoes well, piercing each with a fork several times.
Rub each with olive oil and place on a baking sheet lined with parchment paper. Bake for 1 hour. Remove from oven and let cool for about 5 minutes.
Cut potatoes in half, long ways, scooping out the insides of each and placing into a large mixing bowl. Add buttermilk, butter, garlic, and 1/3 Cup of sour cream. Whip to blend until creamy. Stir in chives and bacon pieces.
Spoon mashed potatoes back into potato shells, then top with shredded cheese.
Return to oven and bake 15-20 minutes until cheese is melted and bubbly.
Serve each with a generous squeeze of sour cream on top of each. Enjoy!