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Rich Potato Gratin Recipe

4.5 from 55 reviews

Rich Potato Gratin is a decadent, creamy dish featuring thinly sliced potatoes layered with a luscious gruyere cheese béchamel sauce, baked until tender and golden brown. This classic French-inspired comfort food combines aromatic sautéed onions, garlic, fresh thyme, and a hint of nutmeg to create a deeply flavorful cheese sauce that perfectly complements the tender potatoes. Ideal as a side for special occasions or a cozy family dinner, this gratin delivers a perfect balance of creamy, cheesy richness and subtle herbaceous notes.

Ingredients

Scale

Cheese Sauce

  • 3 tbsp all-purpose flour (or gluten-free flour)
  • 1 1/2 cups milk (or heavy cream for extra richness)
  • 1/2 cup shredded gruyere cheese (freshly grated)
  • 1 pinch ground nutmeg (optional)
  • 1 tsp fresh thyme, chopped (or 1/2 tsp dried)
  • 3 tbsp unsalted butter (preferably Kerrygold)
  • 1 small onion, minced
  • 1 garlic clove, grated or minced
  • Salt and black pepper, to taste

Potato Base

  • 4 lb potatoes, thinly sliced (about 1/8-inch thick)
  • 1 cup shredded gruyere cheese (freshly grated)

Instructions

  1. Prepare Mise en Place and Preheat Oven: Preheat the oven to 350°F (175°C). Slice the potatoes into thin 1/8-inch rounds using a mandoline or similar tool for even thickness. Mince the onion, grate the garlic, chop the thyme, and shred the gruyere cheese. Having all ingredients ready helps streamline the cooking process.
  2. Build the Béchamel Base with Aromatics: In a medium saucepan over medium heat, melt the butter. Add the minced onion, grated garlic, and chopped thyme. Sauté gently for 3 to 5 minutes until the onion is translucent but not browned, infusing the butter with aromatic flavors.
  3. Make the Cream Sauce: Sprinkle the flour over the aromatic mixture and cook, stirring constantly, for 1 minute to form a roux and cook out the raw flour taste. Slowly whisk in the milk (or cream), ensuring no lumps form. Continue whisking for 1 to 2 minutes until the sauce thickens enough to coat the back of a spoon. Remove from heat, then stir in the 1/2 cup shredded gruyere cheese, ground nutmeg, salt, and pepper until the cheese melts and the sauce is smooth.
  4. Layer the Potatoes with Sauce: Butter a baking dish and pour a thin layer of the cream sauce into the bottom. Arrange half of the sliced potatoes in overlapping layers on top of the sauce. Pour half of the remaining sauce over the potatoes. Repeat with the remaining potato slices and the rest of the sauce, filling in gaps to ensure even cooking.
  5. Bake and Finish the Gratin: Sprinkle the remaining 1 cup of grated gruyere cheese evenly over the top of the layered potatoes and sauce. Bake in the preheated oven for 45 to 60 minutes until the potatoes are tender when pierced with a knife and the top is golden brown. For a deeper crust, broil for 2 to 3 minutes while watching carefully to avoid burning. Let the gratin rest for 10 minutes before serving to allow it to set.

Notes

  • For best results, use freshly grated gruyere cheese as it melts better and provides optimal flavor.
  • You can prepare the gratin the night before by baking it fully, then reheating the next day with an additional layer of cheese on top.
  • Using a mandoline ensures uniformly thin potato slices which cook evenly in the gratin.
  • Resting the gratin after baking helps the layers set and makes serving easier.
  • Substitute heavy cream for milk for a richer, creamier sauce.
  • Monitor the gratin carefully during broiling to prevent the cheese from burning.

Keywords: Potato gratin, gratin dauphinois, gruyere potato bake, creamy potato casserole, French potato dish, cheesy potato bake, comfort food side dish