Preheat oven to 400 degrees F.
Put prepared potatoes in an 8 x 8 in. glass dish. Put butter cubes on top of potatoes. Sprinkle bacon bit on top. Cover with aluminum foil and bake in preheated oven for 1 hour or until potatoes are fork tender.
Take potatoes out of oven and top with ranch dressing and cheese. Stir. Put back in oven until cheese is melted about 5 minutes.
