Place the potatoes on a baking sheet. Rub them with the canola oil and bake for 1 hour, making sure they're sufficiently cooked through.
Slice butter into parts. Place in a large mixing bowl and add the sour cream.
Remove the potatoes from the oven once finished cooking. Lower the heat to 350 degrees F.
With a sharp knife, cut each potato in half lengthwise. Scrape out the insides into the mixing bowl, careful not to tear the shell. Lay the hollowed out potato shells on a baking sheet.
Smash the potato insides into the butter and sour cream. Add one cup of the cheese grated, milk, salt, chopped green onions and ground black pepper to taste and mix well.
Fill the potato shells with the filling. Top each potato with the rest of the grated cheese and bake in the oven until the potato is warmed through, 15 to 20 minutes.
