Make the ranch mashed potatoes: Peel potatoes and cut into 1" pieces, then place pieces in a large saucepan and cover with water. Bring water to boil and cook until potatoes are tender when pierced with a fork, about 10 minutes. Drain and place in a large bowl.
Add ranch seasoning and sour cream and mash potatoes until the mixture is thoroughly combined and most of the lumps are gone. Set aside.
Make the rest of the dish: Toss pulled pork with barbecue sauce (as much or as little as you'd like to use). Add it to a large casserole dish, smoothing it to create one even layer. Top with corn, then add a layer of mashed potatoes. Cover with shredded cheese and scallions.
Bake in the oven for 14 to 16 minutes, or until cheese has melted.
Recipe by The Best Video Recipes for All at https://recipes-for-all.com/barbecue-pulled-pork-shepherds-pie/