This Spinach Potatoes Au Gratin with Gruyère is well worth every minute it takes to prepare. The flavors are deep, the textures are smooth, and the overall takeaway is one of over-the-top, comforting deliciousness, and it never disappoints!
Talk about vegetarian comfort food!
This dish is delicious, packed with flavor, and super satisfying, yet not too rich or heavy.
I love the layering process involved in creating this incredible gratin. It's a bit of a project to make it, but I think it's worth it. And, you can make a few days ahead!
First, what is Potatoes Au Gratin?
Au gratin (or gratin), generally refers to a dish with a golden brown top. In this potato and spinach gratin, there's a mixture of half-and-half, herbs and spices that coat thinly sliced potatoes, layered with spinach, topped with grated onion and Gruyère, all beautifully browned in the oven.
The word gratin, also refers to an oval-shaped baking dish -- which is the way you'll typically see most au gratins presented. Though mine is rectangular. 😉
How to Assemble
I've laid out the steps for assembly very carefully for you because much of the success of this gratin is in the layering process. (You'll find the complete instructions below in the recipe card.)
- Add two layers of potato slices that have been soaking the half-and-half-spice-herb mixture, to a 9 x 13-inch casserole dish. Top them with grated onion and Gruyère, followed by fresh spinach.
- Then these three steps are repeated and followed by more potatoes, onions and cheese. It will literally be almost overflowing.
- To compress everything, weigh it down for about an hour with another pan and heavy cans, compacting all of the ingredients together.
Variations
- Feel free to try this with different cheeses and greens.
- While the Gruyère is lovely because it melts perfectly and has a subtly sweet, nut-like flavor, Emmental and Jarlsberg are both great alternatives.
- Other greens to try are kale (I would not use curly) and chard.
Recipe Tips
- This is a recipe where it's especially important to read through all the steps before you get started.
- The thinner you slice the potatoes, the better. If they're super thin, they become almost like flat pasta.
Can you make this gratin ahead of time?
Yes, you can! This is a dish that only gets better with time. You can make the entire thing up to 3 days ahead of time. After it comes out of the oven, let it cool completely, wrap it tightly and keep it refrigerated. Reheat it, covered, in a 375°F oven for about 30 minutes.
Serving Suggestions
- For a vegetarian meal, I serve the potato and spinach gratin as the main course with a vegetable side dish. It's fantastic with oven-charred broccoli, pan-seared oyster mushrooms, and glazed carrots.
- And if keeping it vegetarian isn't important for you, the gratin becomes the side dish, and you can serve it with chicken or meat. It's especially good with Mediterranean Flank Steak, Lavender-Grilled Ribeye, and whole roasted chicken with lemon.
- However you serve it, a salad is always a lovely addition, and frankly, I think it can also totally stand alone.
Must-Try Potato Gratin-Like Recipes
As I said, this recipe takes time. If you enjoy the cooking process and being in the kitchen, this is for you.
Enjoy!
Spinach Potatoes Au Gratin with Gruyère Recipe
Equipment
- 9 x 13 x 3-inch baking dish (ideally 2)
Ingredients
- 1 (approximately 1⅛ pound) onion
- 5 cups half-and-half
- 1 tablespoon garlic, minced
- 1½ teaspoons dried thyme
- ⅛ teaspoon nutmeg
- ¼ teaspoon allspice
- 1½ teaspoons salt
- ½ teaspoon freshly ground black pepper
- 5 pounds Idaho Russet potatoes
- 3 cups tightly packed, fresh spinach leaves, washed and dried
- 3 cups Gruyère cheese, grated
- 2 tablespoons unsalted butter, melted
Instructions
- Grate the onion. Peel the onion and cut it in half or quarters to grate it. A food processor with the grater attachment is easiest. Alternately, you can slice the onion super thinly. Add the grated onion to a strainer over a bowl and set aside.
- Make half-and-half mixture. In a large sauce pot, combine the half and half with the garlic, thyme, nutmeg and allspice. Bring to a boil and then immediately reduce to a low simmer. Simmer until the the mixture has reduced by about ¼, about 25 minutes. Remove from the stove, strain, and add the salt and pepper. Let it cool until it's warm, or to room temperature.
- Slice potatoes and add them to half and half mixture. Peel the potatoes and slice them as thinly as possible, adding them to the half and half mixture as you go. Make sure the slices aren't stuck together and that all of them become well coated with the mixture. (I use the slicer attachment on my food processor for this, but you can also use a Chef's knife or a mandolin.) Let the potato slices soak for about 30 minutes.
Assembly
- Brush a bit of the melted butter on the bottom and sides of an approximately 9 x 13 x 2-inch baking dish.Without wiping them off, add two even layers of the potato slices from the half and half mixture. You should not be able to see the bottom of the dish when you're done. Sprinkle lightly with salt and pepper. DO NOT THROW OUT THE HALF-AND-HALF MIXTURE! Squeeze any remaining liquid out of the onions and sprinkle about ⅓ of them evenly on the potatoes, followed by 1 cup of the Gruyère cheese. Add ½ of the spinach leaves. (They will not lay flat.)Repeat the above layering steps.Add another two layers of the potatoes. Do not worry if nothing is laying flat -- at this point, it will look high and rounded, and likely sitting above the edges of the dish. This is how it should be. Set aside the remaining melted butter, onions, cheese, and all of the half and half mixture.
- Compress. Cover the dish tightly with plastic wrap and put a second dish directly on top -- ideally one that's the same size so the bottom of the top dish is pressing directly onto the plastic-covered, top layer of potatoes. Everything will flatten out at this point. Now weigh down the top dish -- canned food is perfect. Fill the top pan with as many cans as will fit, and place this entire set-up in the refrigerator for 1 hour. Weighing down the gratin is a way to get any excess liquid out of the potatoes. Remove the the gratin from refrigerator and take off the weights and top dish. Keeping it covered with the plastic, holding it over the sink, slowly pour out any excess liquid from one of the corners. You can hold the palm of one hand down of the top surface of the gratin (on the plastic), to be sure nothing slides around.Remove the plastic wrap completely and sprinkle the top with a bit more salt and pepper, and then the remaining onions and cheese.
- Add remaining ingredients. Stir the saved half-and-half mixture to ensure the garlic and herbs are not sitting at the bottom. Pour it into the gratin until it goes about ¾ the way up the sides (it will be about 1½ cups or so). Use a dull knife to move the potatoes a tiny bit along the edges, to be sure it seeps through to the bottom.
- Bake and cool. Drizzle the top with the remaining melted butter, place the pan on a baking sheet and then it in the preheated 375°F oven. Bake for 50 minutes. Then cover the pan loosely with foil and continue to bake for another 25 minutes.If the top of the gratin hasn't become golden brown, place it under the broiler briefly, about 30 seconds. Let the gratin sit for at least 45 minutes before cutting and serving.
NOTES
NUTRITION
Lana
Doesn't this look lovely! I usually make my gratins with milk and plain, but adding spinach and onions can only make them more delicious. See you later at Andrew's!
sippitysup
Green in a gratin is genius. And I love alliteration too. GREG
angie
I made something very similar only difference is i add artichoke hearts and ricotta cheese - kind of tastes like spinach artichoke dip which my husband adores so i made up this dish to give him the taste of artichoke dip in a heartier more filling way.
valentina
Oh Angie, that sounds amazing! I just might slip int he artichokes next time! Yum! 🙂
Linda Taylor
Oh Angie, the addition of artichoke hearts and ricotta sounds amazing! Do you use frozen artichoke hearts? If so, how much and do you adjust the cooking time? Also wondering the amount of ricotta and if necessary to adjust cooking time. Thanks so much!
valentina
Hi Linda -- in case Angie doesn't respond . . .
I'd say you could use frozen artichokes, if you thaw them completely first.Though, I think marinated artichoke hearts, drained, would be even better though. I'd cut them into fourths, removing any tough leaves, and use about 2 cups -- 1 cup evenly distributed under each layer of cheese. For the ricotta, I'd spread about 3/4 cup per cheese layer, and remove about 1/2 cup of the Gruyere from each. I'd also suggest mixing the full amount of ricotta first with 1 egg and seasoning it well with salt and pepper. I haven't done this before, but I think these amounts will probably work. Best of luck and please let me know how it goes if you give it a try. 🙂
David
May I add my 2¢? I have combined potatoes and Jerusalem artichokes (sunchokes) to make a wonderful gratin - sort of a riff on using artichoke hearts!
valentina
David, your 2 cents is always welcome! And I love this idea -- sounds super delicious!
Deb|EastofEdenCooking
It's time for me to start tonight's dinner and I'm very much wishing I had the ingredients to make this lush gratin. The addition of in-season spinach is marvelous.
valentina
Thank you Deb -- for the compliment and for appreciating the huge pile of fresh spinach! 🙂
Allison - Celebrating Sweets
This looks like it's totally worth the work. All those layers look fabulous!
valentina
It's all about the layers. 😉 Thank you!
Jill
Look at that browned crust on top - that's my favorite part! Yum!
valentina
Thanks, Jill. Mine too!
Iryna
Potato Au Gratin is seriously one of my favorite side dishes of all times. In fact, I've just made it for my daughter's birthday last Saturday. I've never thought of adding spinach to it. Great idea! Gotta try it next time!
valentina
Thanks Iryna. I love it almost any which way. Lucky daughter you have. 🙂
Ellen
This has my name written all over it! Such cheesy goodness and so much flavor.
valentina
Many thanks, Ellen! Hope you try it. 🙂
Jessica Levinson
Those layers look so amazing and delicious! Perfect comfort food from a side dish that's certain to steal the show!
valentina
Thanks so much, Jessica!
Patricia@FreshFoodinaFlash
This all sounds yummy. I'm loving the conversation here.
valentina
Me too! 😀 Thx Patricia!
Natalie Ellis
I love the way it is full of potatoes and creaminess, but it isn’t too rich or heavy.
So I guess I have to give it a try to confirm what you said xD
valentina
I hope you do Natalie! 😀 Enjoy!