A fitting side dish for Christmas dinner.
Preheat oven to 350°F.
In a large bowl mix sliced potatoes, sliced onions, butter and garlic salt together. Add salt and pepper to taste.
Grease a large casserole dish. Place potato mixture in casserole. Cover with aluminum foil.
Bake in oven for 40 minutes stirring occasionally.
Remove from oven and remove aluminum foil.
Sprinkle with cheese. Return to oven, uncovered and continue baking until cheese has melted and potatoes are fork tender, approximately 10 minutes.