I love this recipe because it’s timeless and incredibly versatile. The ingredients are simple, but the result feels indulgent and special. I also like how flexible it is with cheeses and add-ins, which makes it easy for me to adapt based on what I have on hand.
Ingredients
(Here’s a tip: Check out the full list of ingredients and measurements in the recipe card below.)
3 tablespoons butter 1 small onion, finely diced 1 clove garlic, minced or grated 1 teaspoon fresh thyme, chopped (or 1/2 teaspoon dried thyme) 3 tablespoons flour (gluten-free if needed) 1 1/2 cups milk or heavy cream 1 1/2 cups gruyère cheese, shredded 1 pinch nutmeg (optional) Salt to taste Black pepper to taste 4 pounds potatoes, thinly sliced
Directions
I start by melting the butter in a saucepan over medium heat. I add the diced onion and cook it until tender, usually about 3 to 5 minutes.
Next, I stir in the garlic and thyme and cook until fragrant. I sprinkle in the flour, mix well, and cook briefly until it turns lightly golden.
I slowly add the milk and cook, stirring constantly, until the sauce thickens. I reduce the heat and mix in about 1/2 cup of the shredded cheese, letting it melt into the sauce. I then add the nutmeg, salt, and black pepper to taste.
I spread a small amount of sauce over the bottom of a large baking dish. I layer the sliced potatoes in the dish, adding sauce between layers. I like dipping each potato slice into the sauce before placing it in the dish to ensure even coverage.
Once all the potatoes are layered, I pour the remaining sauce over the top and sprinkle on the rest of the cheese. I bake the gratin in a preheated 350°F oven for 45 to 60 minutes, until the potatoes are tender and the top is lightly golden.
Servings and Timing
This recipe serves about 8 people. Preparation time: 20 minutes Cooking time: 1 hour 10 minutes Total time: approximately 1 hour 30 minutes
Variations
I sometimes replace the milk and flour with heavy cream for an even richer sauce. I like experimenting with different melting cheeses such as Swiss, mozzarella, Havarti, or cheddar. Adding Parmesan, Asiago, or Pecorino Romano gives extra depth. When I want something heartier, I mix in cooked bacon or use Yukon Gold or russet potatoes for slightly different textures.
Storage/Reheating
I store leftover potato gratin in an airtight container in the refrigerator for up to 3 days. When reheating, I prefer the oven at 350°F until warmed through, which helps maintain the creamy texture better than the microwave.
FAQs
Can I make potato gratin ahead of time?
I often assemble it a few hours in advance and bake it just before serving.
What potatoes work best for gratin?
I like using russet or Yukon Gold potatoes, but any potato variety works well.
Can I make this dish gluten-free?
I use a gluten-free flour blend, and the results are just as creamy.
How do I know when the gratin is done?
I check that the potatoes are fork-tender and the sauce is bubbling around the edges.
Can I add protein to this dish?
I sometimes add cooked bacon or ham to make it more filling.
Conclusion
This Potato Gratin is one of my favorite side dishes because it’s rich, comforting, and endlessly adaptable. I love serving it for holidays, dinner parties, or cozy family meals when I want something classic that never goes out of style.
