Make-Ahead Skillet-Baked Cheesy Potato Gratin

This creamy baked potato gratin composed of thinly sliced potato, heavy cream, and hard cheese is an easy, festive side that can be made ahead of schedule. Parcook the potatoes in sauce until tender, then transfer them to a cast iron dish and top with plenty of cheese. Just pop the whole thing in the oven five to ten minutes before you’re ready to serve, flame cooking until the sauce bubbles and the cheese turns a beautiful golden brown. This recipe uses King Edward potatoes, which are soft and tender, but if you prefer a bit more bite in your gratin, try waxy varieties such as new potatoes, French fingerlings, Red Bliss, Jersey Royals, Adirondack Reds, Russian Bananas (potentially the best-named potato ever?) or others.

Time
45 minutes total time 

Yield 
Serves 2 to 4 as a side

Equipment 

Ooni Pizza Oven
Ooni Sizzler, Skillet, or Grizzler Pan

Ingredients

5 large King Edward potatoes (or waxy alternative), thinly sliced into 2-millimeter discs
¾ cup plus 2 tablespoons (200 grams) whole milk
¾ cup (200 grams) heavy or whipping cream (also known as double cream)
¼ cup (50 grams) butter, plus more for greasing the cast iron
1 to 2 cloves garlic, minced
½ teaspoon (1 gram) flaked sea salt
freshly ground black pepper, to taste
½ tsp (1 gram) ground nutmeg
1 cup (100 grams) grated Gruyère
½ cup (40 grams) shaved or flaked Parmesan 

Method

Fire up your oven. Aim for 430°F (220°C) on the baking stone inside. Use the thermometer to quickly and easily check the temperature.

In a saucepan, add potatoes, milk, cream, butter, and garlic. Season with salt, pepper and nutmeg, then  stir. Bring to a boil over medium heat, then lightly simmer for 8 to 10 minutes. The potatoes should be tender and the sauce slightly thickened. Taste and adjust seasoning as needed. 

Lightly grease the cast iron pan with butter. Pour the potato and cream mix into the pan, spreading evenly using the back of a spoon. Sprinkle grated Gruyère and Parmesan over the top. 

Cook in your Ooni oven for 5 to 6 minutes, turning the pan every 2 minutes, until the sauce is bubbling and the cheese has turned a deep golden brown. Let cool for a couple of minutes before serving.