Here is potatoes au gratin without the slicing

Super Easy Potatoes Au Gratin
Serves 6

6 medium baking potatoes
2 cups cheddar cheese, shredded
4-5 tablespoons butter
1-1/2 cups fat-free sour cream
3 green onions; chopped
Salt and ground black or red pepper to taste

Cook potatoes in skins, cool. Peel and shred into a large bowl, on a coarse grater. 

Preheat oven to 325ºF.  

Combine 1¼ cups cheese and 3 tablespoons butter in saucepan; heat and stir until cheese is almost melted. Remove from heat.  

Blend in sour cream, onion, salt, and pepper. Fold in potatoes.  Spoon into a greased 2-quart casserole dish. Dot with 1-2 tablespoons butter and sprinkle the remaining cheese on top.  

Cover with aluminum foil and bake about 20-25 minutes.  Remove foil and continue baking about 5-8 minutes or until cheese is slightly browned in spots.