Spray baking dish, 11x15 pan, with cooking spray (or you can use a 1/2 sheetcake pan). Preheat oven to 375.
Toss together Potatoes, Onions Cheese & Salt in separate bowl.
Place potato mixture in the 11x15 pan and pour whipping cream and half & half over the top.
Cover with foil and bake at 375 for 2 hours. (Stir once after the first hour).
All ingredients are available at Samrt & Final. Onions already diced and cheese already shredded.