Preheat oven to 400 and place the potatoes on a large sheet pan. Using a fork, pierce each potato about 6 times (so that the potatoes can steam while cooking). Transfer to the oven and bake until the potatoes are cooked through and are easily pierced with a fork, about 45 minutes.
Remove from the oven (keep the oven on) and let rest until just cool enough to handle, about 10-15 minutes.
Meanwhile, heat a skillet over medium heat. Add the bacon and fry until crisp. Set aside on a paper towel-lined plate.
When the potatoes are cool enough to handle but still warm, slice each potato in half lengthwise. Then, using a spoon or an ice cream scoop, scoop out the inside of each potato (forming a boat ) leaving a small amount, about ¼ inch, of the potato on the skin to help it hold its shape more easily.
Pace the scooped-out potato insides in a large mixing bowl along with the sour cream, broth, truffle salt, pepper, 1 cup of the gruyere cheese, and ¼ cup of the chives. Mash until well combined and creamy. *to make mine extra creamy, I like to use my KitchenAid stand mixer with the whisk attachment and whip until creamy and smooth.
Cut the bacon into small bits and add ¾ of the bacon bits to the mixture and stir once more to combine. Reserve the remaining bacon for topping.
Evenly divide the mashed potato mixture back into the potato boats. Sprinkle the tops with the remaining cheese, bacon and the 2 tbsp of chives. Transfer back to the oven and bake until the cheese has melted and is started to lightly brown on the edges, about 15 more minutes.