Three-Potato Gratin

Prep: 15 min Cook: 90 min Serves: 12 Cuisine: American

A rich and creamy three-potato gratin featuring yams and Idaho potatoes, infused with thyme and Dijon mustard, perfect for comforting family dinners or special occasions.

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Ingredients

  • 1 Tbsp. butter
  • 2 1/2 c. heavy cream
  • 1/4 c. Dijon mustard
  • 1 1/2 tsp. cornstarch
  • 1 tsp. salt
  • 1/2 tsp. pepper
  • 1 1/4 lb. yams, peeled and thinly sliced
  • 1 1/4 lb. Idaho potatoes, peeled and thinly sliced

Instructions

  1. Preheat oven to 325°F.
  2. Grease a 3-quart shallow baking dish with butter.
  3. In a bowl, mix heavy cream, Dijon mustard, cornstarch, salt, and pepper.
  4. Add sliced yams and Idaho potatoes; toss to coat.
  5. Pour the mixture into the prepared dish.
  6. Cover and bake for 1 hour.
  7. Uncover and bake for an additional 30 minutes or until potatoes are tender and golden.
  8. Let sit for 10 minutes before serving.
  9. Sprinkle with crumbled fresh thyme leaves.

Tips & Substitutions

For a richer flavor, consider using a blend of heavy cream and whole milk. If you want to lighten the dish, you can substitute half of the heavy cream with low-fat milk. Sweet potatoes can be used in place of yams for a different taste. Make sure to slice the potatoes thinly for even cooking; a mandoline can help achieve uniform slices.

Serving Suggestions

This Three-Potato Gratin pairs beautifully with a simple green salad or roasted vegetables for a complete meal. It also complements grilled meats or fish. For an extra touch, serve it alongside Parmesan Corn as a delightful side dish. Garnish with fresh thyme or parsley to enhance presentation.

Storage & Reheating

Store any leftovers in an airtight container in the refrigerator for up to 3 days. To reheat, place the gratin in a preheated oven at 350°F for about 20-25 minutes, covered with foil to prevent drying out. You can also microwave individual portions for a quick meal.

Nutrition & Diet Analysis (per serving)

Each serving of Three-Potato Gratin contains roughly 458 calories, with 1g protein, 3g carbohydrates, and 49g fat. It is an excellent source of vitamin C (46% of the Daily Value). Note that it is relatively high in sodium, at 603mg per serving (26% of the Daily Value).

458 kcal 23% DV
Protein Fat Carbs

Macronutrients

Protein 1g 2% DV
Total Fat 49.3g 63% DV
Carbs 3.3g 1% DV
Fiber 1.8g 6% DV
Sugar 1.1g 2% DV

Electrolytes

Sodium 603.1mg 26% DV
Potassium 136.1mg 3% DV
Cholesterol 147.4mg 49% DV

Vitamins & Minerals

Vitamin A 29.6mcg 3% DV
Vitamin C 41.7mg 46% DV
Vitamin D 0.1mcg
Calcium 12.3mg 1% DV
Iron 0.3mg 2% DV
Diet fit Keto-friendly
Contains Milk

Estimated from ingredients & per-serving nutrition — verify against package labels for allergies or strict diets.

* % Daily Values based on a 2,000 calorie diet (FDA 2020).

Frequently Asked Questions

Can I prepare this gratin in advance?

Yes, you can assemble the gratin a day ahead. Just cover it tightly with plastic wrap and refrigerate. When you're ready to bake, remove from the fridge for 30 minutes before cooking to ensure even baking. This is a great time-saver for gatherings!

What can I use instead of Dijon mustard?

If you don't have Dijon mustard on hand, you can substitute it with whole grain mustard or yellow mustard. For a milder flavor, consider using a small amount of apple cider vinegar mixed with plain yogurt or sour cream to achieve a similar tangy taste.

Is this dish suitable for vegetarians?

Yes, this Three-Potato Gratin is a vegetarian recipe. It contains no meat, making it a great option for those following a vegetarian diet. Just ensure the heavy cream used is not mixed with any animal rennet if strict vegetarianism is a concern.

Nutrition is estimated from USDA FoodData Central ingredient data and may vary with brand, portion and preparation — see our methodology. This information is for general educational purposes only and is not medical or dietary advice (disclaimer).

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