Thoroughly wash and dry potatoes and rub with oil and salt.
Wrap potatoes in foil and bake in an oven at 200°C until done for about 1 hour. Let potatoes cool for 15 minutes.
For each potato, cut off the top quarter (long ways). Remove and discard the peel from that piece and keep the pulp in a bowl. Using a melon baller or large spoon, scoop out the potato pulp and add to the bowl.
Add the remaining stuffing ingredients except the butter into a bowl and thoroughly mix together, smashing with a fork. Spoon the mixture back into the potato shells.
Top with a little extra shredded cheese and drizzle with butter.
Cook the stuffed potatoes on an indirect grill (or oven) preheated to 176°C until cooked through, about 20 minutes if potatoes are warm, 30 minutes if potatoes are made ahead of time and refrigerated.