This is a wonderful dish for special occasions. If you’re eating low carb, substitute cauliflower, sliced into flat pieces, and use 100% cream.
Potatoes Au Gratin
2 tablespoons unsalted Kerrygold butter
1 small onion (100g/1/2 C.), minced (or 2 teaspoons onion powder)
2 cloves (2 tsp.) garlic, minced (or 2/3 teaspoon garlic powder)
3 cups grass-fed heavy cream
1 cup grass-fed whole milk (or half-and-half)
4 sprigs fresh thyme (or 1 tablespoon dried)
2 bay leaves
2 teaspoons sea salt
1/2 teaspoon ground black pepper
3.5—4 pounds russet potatoes, peeled and cut into 1/8-inch-thick slices
1 cup (or more) gruyere cheese, shredded (about 4 oz.)
1/4 cup Parmesan, grated
Note: For the fastest and most consistent results, slice the potatoes in a food processor using a 4mm (1/8”) disc.
Heat oven to 350 degrees.
Melt butter in 12-inch ovenproof skillet (I use a big ol’ cast iron pan) over medium-high heat until foaming subsides, about 1 minute. Add onion and sauté until it turns soft and begins to brown, about 4 minutes. Add garlic and sauté until fragrant, about 30 seconds. (If using onion and garlic powder, add them when adding the cream) Place sliced potatoes in overlapping circles in the pan, then add cream and milk (or half-and-half), thyme, bay leaves, salt, pepper, and bring to simmer. Cover, adjusting heat as necessary to maintain light simmer, and cook until potatoes are almost tender (paring knife can be slipped into and out of center of potato slice with some resistance), about 15 minutes.
Remove and discard bay leaves and thyme sprigs (If you used dried thyme, just leave it in). Sprinkle with cheese.
Place skillet in oven and bake until cream has thickened and is bubbling around sides and top is golden brown, about 20 minutes. Remove from oven, sprinkle with Parmesan, and run under the broiler until golden.
Cool for 5 minutes before serving.
MAKE AHEAD INSTRUCTIONS
Once the scalloped potatoes are ready for the oven, they can be wrapped in plastic wrap and refrigerated for up to 24 hours. When ready to bake, pop in a 400-degree oven and cook until the mixture is hot and bubbling, about 30-45 minutes. Remove from oven, sprinkle with Parmesan, and run under the broiler until golden. Let cool for 10 minutes before serving.