2Grease 9 X 13 baking pan with cooking spray on the bottom. Cover the bottom of pan with a layer of potatoes, sprinkle salt and pepper, some of the garlic and onion and half of the mushrooms, add pats of butter and then layer slices of swiss cheese
Do another layer but using shredded cheese, the last layer should be the remainder of the potatoes and cheese. Pour the pint of whipping cream over the top. Bake 1 hour and the check the potatoes with a sharp knife to check to see if potatoes are cooked through, if not bake for another 1/2 hour (Depends on oven) Remove from oven, casserole will be bubbling and cheesy. I always let it sit for 10 minutes or so to let it set and cool a bit.
I hope that you enjoy!