1 tsp unsalted butter 4 cups heavy cream 2 tsp sea salt, divided 1 tsp black pepper 3-1/4 lb Idaho potatoes, peeled and cut into 1/4” slices 8 oz gruyere cheese, grated 8 oz swiss cheese, grated
Preheat oven to 400-deg. Lightly grease a 2 qt baking dish with the butter and set aside.
In a large saucepan, bring the cream to a boil over medium-high heat. Add the salt and pepper and stir well.
Add the potatoes, making sure the cream covers them completely. (Note: add more cream if necessary.) Lower the heat to medium-low and simmer until the potatoes are soft, about 10-12 minutes. Then remove the pan from heat.
Using a spoon, transfer 1/3 the potatoes and cream to the baking dish, arranging them in an even layer. Top with a third of the swiss and gruyere, then repeat until all the potatoes and cheese have been used.
Roast in the oven until golden and crispy on top, about 35 minutes. Then remove from the oven and let stand 5 minutes before serving.