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low FODMAP Potato Cheese Gratin with Mushrooms in casserole dish and on green plate

Low FODMAP Potato Cheese Gratin with Mushrooms

Looking for a comfort-food potato gratin - with a twist? Ours has low FODMAP oyster mushrooms, too.

Course: Dinner, Side Dish
Cuisine: American
Prep Time: 15 minutes
Cook Time: 40 minutes
Total Time: 55 minutes
Makes: 14 Servings
Calories: 175 kcal
Author: Dédé Wilson


  • 3 tablespoons Garlic-Infused Oil, made with olive oil, or purchased equivalent, divided
  • 6- ounces (170 g) cleaned oyster mushrooms, chopped
  • 2 pounds (910 g) yukon gold potatoes, peeled
  • 3 cups (720 ml) lactose-free half-and-half, at room temperature
  • 1 teaspoon kosher salt
  • Freshly ground black pepper
  • 1/4 pound (115 g) Gruyere cheese, grated


  1. Position rack in middle of oven. Preheat the oven to 400°F/200°C. Use 1 tablespoon of Garlic-Infused Oil to coat the inside of a 3-quart (2.8 L) shallow casserole dish; set aside.
  2. Heat remaining 2 tablespoons of oil in a large sautepan (I use a 3-quart/2.8 L) and heat over medium heat. Add chopped mushrooms and saute until softened, just a few minutes, then remove from heat. Set aside.

  3. Cut the potatoes very thinly into 1/8-inch (3 mm) rounds using a very sharp knife, a mandoline, or the slicing disc of a food processor.
  4. Add the potatoes to the saucepan then add the half-and-half, salt and generous amount of pepper. Bring to a vigorous simmer over medium heat, shaking the pan occasionally, and simmer for 3 minutes.

  5. Carefully scoop and pour the mixture into prepared casserole dish. Gently coax the potatoes, mushrooms and liquid into an even layer. Sprinkle the cheese evenly over the top.

  6. Bake for about 35 to 45 minutes or until the potatoes are tender when pierced with a knife and the top is golden and bubbling. The mixture might look a little loose, but don’t worry, it will firm up upon cooling. Place casserole on a rack and cool for at least 15 minutes to allow the gratin to achieve its maximum potato perfection. Serve warm or even at room temperature.


If You Can Tolerate

  • Lactose: if you have passed the lactose challenge, feel free to use conventional half-and-half in the same amount.
Nutrition Facts
Low FODMAP Potato Cheese Gratin with Mushrooms
Amount Per Serving
Calories 175 Calories from Fat 99
% Daily Value*
Fat 11g17%
Sodium 168mg7%
Carbohydrates 14g5%
Fiber 2g8%
Sugar 1g1%
Protein 5g10%
* Percent Daily Values are based on a 2000 calorie diet.