If you’re in search of a comforting and elegant side dish that brings vibrant color and creamy richness to your table, look no further than this Spinach Gratin Recipe. It’s a classic, soul-satisfying casserole bursting with tender spinach enveloped in a luscious, cheesy sauce. Whether you’re serving it alongside a festive dinner or just craving a cozy veggie indulgence, this dish manages to be both simple to prepare and impressive to present, making it an absolute favorite to keep in your culinary repertoire.

The image shows a white round plate holding a layered spinach and cheese dish. The bottom layer is dark green cooked spinach with a soft, slightly wet texture. Above the spinach, there is a thick layer of melted cheese that is golden brown on top, bubbly, and creamy white underneath. The cheese layer covers most of the spinach and has a few browned spots, giving it a rich and baked look. The plate is on a white marbled surface, and a silver fork and spatula rest near the top of the plate, catching light and adding a shiny contrast. photo taken with an iphone --ar 4:5 --v 7

Ingredients You’ll Need

This Spinach Gratin Recipe calls for a handful of humble yet crucial ingredients that work in harmony to create its rich texture and irresistible flavor. Each element adds its own magic—from the sweetness of onions to the nutty depth of Parmesan, making the dish both comforting and elegantly nuanced.

Unsalted butter: Provides a creamy base for sautéing and adds richness without overpowering flavors.
Yellow onion: Finely diced to impart a natural sweetness that balances the spinach’s earthiness.
Garlic clove: Minced to introduce a subtle aromatic punch that elevates every bite.
All-purpose flour: Acts as the thickening agent for the creamy sauce, creating that perfect gratin consistency.
Milk: The main liquid that turns the flour into a velvety béchamel-style sauce.
Kosher salt: Enhances flavors thoughtfully without making the dish salty.
Nutmeg: A pinch adds warm spice that complements the creamy sauce and spinach beautifully.
Frozen chopped spinach: Defrosted and drained to ensure the gratin isn’t watery and stays perfectly creamy.
Parmesan cheese: Grated into the sauce for umami depth and a naturally salty tang.
Black pepper: Freshly cracked for a mild heat that brightens the dish.
Monterey Jack or Gruyere cheese: Shredded and sprinkled on top to create a glorious golden crust.

How to Make Spinach Gratin Recipe

Step 1: Sauté the Aromatics

Start by preheating your oven to 400 degrees and prepping a 2-quart casserole dish with some cooking spray to prevent sticking. Melt the butter in a large skillet over medium heat, then add the finely diced onions. Cook them for 3 to 4 minutes until they turn translucent and soft, releasing their natural sweetness. Toss in the minced garlic and cook just for another minute to unlock those fragrant oils that will infuse the dish.

Step 2: Create the Creamy Sauce

Sprinkle the flour over the softened onions and garlic, stirring constantly for about a minute—this step is crucial to remove any raw flour taste and create a smooth base. Then slowly whisk in the milk along with kosher salt and a hint of nutmeg. Bring the mixture to a gentle bubble before lowering the heat and letting it simmer quietly for 10 minutes, stirring often to avoid burning and to help it thicken into that luscious béchamel sauce we all love.

Step 3: Prepare the Spinach Mixture

The key to this Spinach Gratin Recipe is squeezing out every last bit of moisture from your defrosted spinach. Excess liquid will turn your gratin watery, and we do not want that! Once your spinach is well drained, stir it into the cream sauce along with the grated Parmesan cheese. Mix everything until fully combined, then taste and adjust the salt and pepper if needed—this mixture should be flavorful and cohesive.

Step 4: Bake to Perfection

Pour the rich spinach and cheese mixture into your prepared casserole dish. Evenly sprinkle shredded Monterey Jack or Gruyere cheese on top to encourage a beautifully browned crust. Bake uncovered for 28 to 30 minutes, or until the cheese on top is golden and bubbling with anticipation. Remove from the oven and let it settle briefly before serving.

How to Serve Spinach Gratin Recipe

Garnishes

While the gratin itself shines as the star, a sprinkle of freshly chopped parsley or chives can add a pop of bright color and freshness. A light dusting of extra Parmesan right off the bat also adds a nice little savory kick.

Side Dishes

This Spinach Gratin Recipe pairs exquisitely with hearty roasted meats like chicken or pork, as well as alongside a simple quinoa salad or crusty bread to round out a meal. It can easily be the comforting accompaniment you didn’t realize you needed.

Creative Ways to Present

For special occasions, consider serving this gratin in individual ramekins or mini cocottes—this adds a beautifully rustic yet refined touch. You can even layer the spinach gratin with slices of sautéed mushrooms or caramelized onions for an elevated twist that will wow your guests.

Make Ahead and Storage

Storing Leftovers

Leftover spinach gratin holds up well in the refrigerator for up to 3 days when stored in an airtight container. Just be sure to let it cool completely before sealing to preserve its creamy texture.

Freezing

If you want to keep it longer, this gratin freezes beautifully. Transfer cooled portions to freezer-safe containers and freeze for up to 2 months. It’s a fantastic make-ahead option for busy weeknights or impromptu gatherings.

Reheating

To reheat, thaw overnight in the fridge if frozen, then warm in a 350-degree oven until heated through and bubbly again. Avoid microwaving if possible to keep the creamy texture intact and the cheesy crust slightly crisp.

FAQs

Can I use fresh spinach instead of frozen?

Absolutely! If you have fresh spinach, wilt it down in a pan first and squeeze out as much liquid as possible before using in the gratin—this step is essential to avoid a watery dish.

Is there a vegetarian version of this recipe?

This Spinach Gratin Recipe is already vegetarian-friendly as it contains no meat. Just ensure that the cheeses you choose are suitable for vegetarians if that is a concern.

Can I substitute the milk for a dairy-free alternative?

You can try using unsweetened almond or oat milk, but be aware that the creaminess might be slightly different. Adding a bit of dairy-free butter can help mimic the richness.

How can I make the gratin crispier on top?

Using Gruyere cheese tends to create a nice crust, but you can also sprinkle some breadcrumbs mixed with melted butter on top before baking to add an extra crunch.

Can I add other vegetables to the gratin?

Definitely! Mushrooms, leeks, or artichoke hearts complement spinach nicely and can be sautéed and folded into the sauce for extra flavor and texture.

Final Thoughts

This Spinach Gratin Recipe is such a wonderful way to celebrate one of our favorite greens with a creamy, savory twist that feels like a warm hug on a plate. Whether you’re making it for a casual dinner or a holiday feast, it’s sure to become a new go-to favorite. So grab your ingredients, get cooking, and prepare to wow yourself and your loved ones with this irresistible dish!

Spinach Gratin Recipe