

Preheat oven to 425°F.
Wash and scrub potatoes thoroughly. Pat dry. Prick the potato skins with the tines of a fork. Rub olive oil all over the surface of each potato until fully coated and season with salt.
Bake the potatoes on a baking sheet for about 45 minutes to 1 hour, until they can be pierced easily with a fork.
While potatoes are cooking, heat 1 Tbsp olive oil in a large skillet. Add the diced pancetta and cook until slightly crispy. Remove from pan. Add the onions and peppers to the pan and cook over medium-low heat for 10-15 minutes, stirring occasionally. Add salt and pepper to taste. Add 1 Tbsp butter and cook for an additional 3-4 minutes or until onions and peppers are soft and golden brown. Set aside.
Bring a pot of water to a boil, add 1 Tbsp salt and prepared Yukon gold potatoes. Boil until soft and tender, about 10 minutes. Strain potatoes and add to the bowl of a stand mixer.
When baking potatoes are done, remove from oven and allow to cool for a few minutes. Keep oven on. Using a sharp knife and an oven mitt to protect hands, slice each baked potato in half lengthwise to create a long boat. Scoop cooked flesh out of each potato half, leaving a ¼ of potato around the rim and bottom to keep skin intact. Add scooped potato to the stand mixer bowl with the boiled potatoes. Add 4 Tbsp butter and milk to potatoes. Add more salt and pepper to taste.
Using the whisk attachment, begin mixing the potatoes on low speed. As the potatoes begin to become smooth, increase speed, adding remaining 3 Tbsp of butter and more milk if they are too dry. Add Mascarpone cheese and whip for another minute. Stir in shredded Parmesan and crispy pancetta, reserving 3 Tbsp of each for garnishing.
Using a pastry bag with a wide opening or a large spoon, scoop heaping spoonfuls of whipped potatoes into the prepared potato skins. Bake stuffed potatoes in oven again until heated through, about 10 minutes.
Arrange some of the caramelized onions and peppers atop each potato. Sprinkle with more shredded Parmesan and sprinkle with paprika.
Broil potatoes in the oven again until cheese is melted, about 2 minutes. Sprinkle reserved pancetta atop and serve immediately.