Preheat the oven to 400 degrees. Rub the potatoes lightly with olive oil and bake them on a foil-lined baking sheet until their skins are crisp and a fork easily slides into their flesh, about 1 hour. Transfer the potatoes to a wire rack and let cool for 10 minutes
While the potatoes are cooking, assemble the toppings. Cook the bacon in a large skillet over medium heat or in oven until crisp, then transfer to a small bowl. Reserve the bacon fat. Grate the cheese into a small bowl; you should have about 2 cups. Trim and thinly slice the chives or scallions.
Using an oven mitt or a folded kitchen towel to handle the hot potatoes, cut each into quarters lengthwise to create four wedges. Using a small spoon, scoop some of the flesh from each wedge, leaving 1/4 inch or more of the flesh
Set the oven to broil. Return the wedges to the foil-lined baking sheet. Paint a bit of bacon fat on each, then top with cheese and bacon. Place under the broiler until the cheese is bubbling
Place the skins on a serving plate. Season with salt and pepper. Spoon a teaspoon or so of crème fraîche or sour cream on each and scatter the chives or scallions over the plate. Serve with hot sauce (optional)