Spread leftover garlic and herb potatoes in 9x12 casserole dish. I used Betty Crocker instant potatoes. Slice baked potatoes with peeling on top of mashed potatoes. Salt and pepper to taste. Spread undiluted cream of mushroom soup over sliced potatoes. Top with cheddar cheese. Be creative if your taste likes sharp cheddar use it. I used Medium. Use one stick of butter sliced on top about 8 to 10 slices. Bake for 25 to 30 minutes. This is already cooked, so it may take less time in your oven. This is comfort food at it's best...Enjoy!