Preheat an oven to 400 F.
Prep the potatoes. Scrub the potatoes of any dirt and rinse them under cold water. Pat them very dry and place them on a rimmed baking sheet. Use a fork to poke holes all over the potatoes, then drizzle the oil all over them. Use your hands to rub the oil into the potatoes, then sprinkle the outsides all over with salt and pepper.
Bake the potatoes. Bake the potatoes for 45 minutes, or until they’re tender enough to be pierced with a knife. Remove the potatoes from the oven and let them cool for 15 minutes.
Scoop out the insides. Carefully cut the top 1/4 lengthwise off the potatoes to expose the middle. Use a spoon to scoop out the inside of the potato, leaving a 1/4 inch border of potato to create little boats.
Mix the potato filling. Place the scooped potato in a mixing bowl with the minced bacon, chives, boursin, and gruyere. Don’t forget to scrape any potato from the portion you cut off the tops, then discard the skin. Use a hand mixer to beat the potato mixture, drizzling in the heavy cream while doing so, until the filling is very smooth and the boursin is melted. The filling should be soft and pipe-able, so add as much cream as necessary. Season to taste with salt and pepper.
Bake the potatoes. Transfer the filling to a piping bag fitted with a large star tip and pipe the filling back into the potato boats so that they’re decoratively mounded. You can also use a spoon to mound the filling back into the potatoes. Gently brush the tops with the melted butter and place them back into the oven on a baking sheet for 15 minutes, until the tops are just starting to brown and the potatoes are warmed through. Top with more chives and serve right away.