Preparation Steps

• Preheat the Oven: Set your oven to 325°F (163°C).
• Infuse the Cream: In a small saucepan, combine the heavy cream, kosher salt, and minced garlic. Simmer over low heat for 5 minutes to allow the garlic to infuse the cream. Remove from heat and set aside.
• Prepare Potatoes: Using a mandoline slicer, thinly slice the potatoes to a thickness of ⅛ inch.
• Sauté Shallots: In a 12-inch cast iron pan, melt the butter over low heat. Add the diced shallots and sauté until caramelized, about 5 minutes.
• Layer the Potatoes: Arrange the sliced potatoes in a spiral pattern over the caramelized shallots in the cast iron pan.
• Add Cream: Pour the infused cream mixture evenly over the potatoes.
• Bake: Cover the pan tightly with aluminum foil and bake in the preheated oven for 1 hour and 15 minutes.
• Broil the Cheese: Remove the pan from the oven and increase the oven temperature to broil. Uncover the potatoes and top with grated Gruyere and Parmesan cheeses. Sprinkle with fresh thyme.
• Finish Under Broiler: Return the pan to the oven and broil for 5 minutes, or until the cheese is crispy and bubbling.
• Serve and Store: Remove from the oven and serve warm. Leftovers can be stored in the refrigerator and reheated the next day.