Preheat oven to 350degreesF.
Using a fork gently prick holes throughout each potato and individually wrap them in aluminum foil.
Place the wrapped potatoes onto a baking sheet and place in the oven.
Bake for 40 minutes to an hour, or until the potatoes are fork tender.
Remove the foil from the potatoes and allow to cool for about 20 minutes.
Carefully make an insertion halfway through each potato and carefully scoop the flesh into a large bowl.
Once all the potatoes have been hollowed out, add the butter, milk and sour cream to the bowl and mash with a potato masher until smooth. Season with salt and pepper.
Gently fold the goat cheese, pancetta, chives, thyme, chervil, and garlic into the potato mixture until fully incorporated. Adjust the seasonings.
Carefully scoop the mixture back into four of the potato skins, discarding the other two skins, until each potato is barely overflowing. Set aside. (If a piping bag is available, the mixture can be piped back into the skins.)
In a small bowl, combine the chorizo and fontina, toss together.
Top each potato with 2 tablespoons of the chorizo and cheese mixture.
Place the prepared potatoes onto a parchment lined baking sheet and bake for an additional 15 minutes.
Transfer the potatoes to the broiler and broil on high for 1 to 2 minutes or until the tops become golden brown and develop and light crust.
Allow the potatoes to cool for 5 minutes and serve hot.