Clean and cut baby potatoes into half. If the potatoes are big cut into quarters.
Heat oil in an ovenproof skillet / cast iron skillet. Add potatoes. Season with pepper. Add stock to it and cover.
Cover and let the potatoes cook until it is nearly done. It should take 8-10 minutes. Switch of the gas. It is ok if there is some stock left in the skillet.
Add ranch dressing and half of the cheese to the skillet. Mix well.
Sprinkle the rest of the cheese and bake for 20 minutes.