Sometimes the classics are the way to go. If you intolerant of dairy there are many alternatives, the easiest one is LACTOSE free products, or vegan substitutions. This is a favourite of mine with wonderful childhood memories of Sunday Roasts.
2 tablespoons/30ml olive oil
2 tablespoons/30g butter
2 pounds/900g yellow or red (waxy) potatoes, sliced thinly
1 teaspoon/5ml sea salt
½ teaspoon/2ml white pepper
8 ounces/225g grated swiss cheese
1 ¼ cups/310ml heavy cream
Pre-heat oven to 300F/149C/Gas Mark 2
Pour olive oil in 10 x 7 inch (28 x 18 cm) baking dish. Stack single layers of potatoes, seasoning each layer with salt and pepper, dotting with butter and sprinkling with cheese. The last layers should be butter and cheese. On the stove top, bring the cream to a simmer. Pour cream over the potatoes. Place the potatoes in the oven and bake uncovered for 1 to 1 ½ hours. The potatoes will be easily pierced with a fork and the top browned.