The Ultimate Easy Creamy Spinach Gratin

This isn’t just another creamed spinach. This is the dish you make when you want serious comfort food. It’s the side that steals the show from the main course. It’s rich, cheesy, and feels incredibly indulgent, yet it comes together so quickly you’ll feel like you cheated.

Why This Recipe Is a Keeper

I could go on forever, but here’s why I think you’ll fall in love with this gratin:

• Unbelievably Rich Flavor: We’re not using just one cheese; we’re using three! The combination of nutty Gruyère, salty Parmesan, and velvety mascarpone creates a sauce with incredible depth. The hint of leek and thyme adds a subtle, savory backbone that cuts through the richness perfectly.
• One-Pan Wonder: If you use a cast-iron or other oven-safe skillet, this entire dish comes together in one pan. Sauté on the stove, then pop it straight into the oven to bake. Fewer dishes are always a win in my book!
• Low-Carb, High-Comfort: It’s naturally low-carb and keto-friendly, but it’s so satisfying that no one will ever know. The crunchy pork rind topping is a game-changer, but it’s super easy to swap out if you need a vegetarian option.

What You’ll Need

Here’s a quick look at our ingredient lineup. Don’t be intimidated by the list; it all comes together in a flash!

• Olive Oil: Just a tablespoon for getting our aromatics started.
• Leek & Garlic: The flavor foundation. Leeks offer a milder, sweeter onion flavor that’s just perfect here.
• Frozen Chopped Spinach: The star of the show! Using frozen is a huge time-saver. Just make sure you squeeze it really dry.
• The Cheeses (Mascarpone, Gruyère, Parmesan): Our holy trinity of creaminess and flavor. Don’t skimp here! Grating your own cheese from a block will give you the best melt.
• Heavy Cream: This is what creates that luxurious, velvety sauce.
• Herbs & Spices: Dried thyme, grated nutmeg, sea salt, and black pepper. The nutmeg is a classic addition to cream sauces and adds a wonderful, subtle warmth.
• Crushed Pork Rinds: My secret weapon for a crunchy, keto-friendly topping.

Step-by-Step Guide to Perfection

1. Get Ready: First things first, get your oven preheating to 375°F with the rack in the middle. While that’s heating up, mix your crunchy topping. In a small bowl, just toss together the crushed pork rinds, half of the Gruyère, and half of the Parmesan. Set it aside for now.

2. Build the Flavor: In a 10-inch cast-iron skillet, warm the olive oil over medium heat. Add your chopped leek and let it cook for 3-4 minutes until it’s nice and soft. Then, stir in the pressed garlic and dried thyme and cook for about 45 seconds more—just until you can smell that amazing aroma.

3. Dry Out the Spinach: Now, add your very dry squeezed spinach to the skillet. Stir it around for a couple of minutes to heat it through and cook off any last bit of water. This step is key to avoiding a watery gratin!

4. Create the Creamy Sauce: Turn the heat down to low. Add the mascarpone, heavy cream, salt, pepper, and nutmeg right into the skillet with the spinach. Keep stirring until the mascarpone melts completely and you have a gorgeous, smooth sauce coating every bit of spinach.

5. Add More Cheese! Take the skillet off the heat and stir in the rest of your Gruyère and Parmesan. You just want to mix until they’re melted and combined.

6. Bake It Up: Smooth the top of the spinach mixture and sprinkle that yummy crumb topping you made earlier all over it. Slide the skillet into the oven and bake for 20-25 minutes. You’re looking for bubbling edges and a golden-brown top.

7. Give It a Final Crisp: For that extra-crispy, restaurant-quality finish, turn the oven to broil for the last minute or two. Watch it like a hawk here, as it can go from golden to burnt in seconds! Let it rest for 5 minutes before you dig in; this lets the sauce set up a bit.

Expert Tips for Success

• The Squeeze is Everything: I can’t say it enough: get as much water out of your thawed spinach as possible. A cheesecloth or a potato ricer works wonders if you want to be extra thorough.
• Vegetarian Swap: To make this vegetarian, simply swap the crushed pork rinds for two tablespoons of almond flour, panko breadcrumbs, or finely chopped walnuts for the topping.
• Storage and Reheating: Leftovers are fantastic! Store them in an airtight container in the fridge for up to 3 days. To reheat, just pop it in a 350°F oven until it’s hot and bubbly again.

Serving & Pairing Ideas

This gratin is a dream side dish for almost any protein. It’s absolutely perfect alongside a roasted chicken, a juicy steak, or a simple piece of baked salmon. For a cozy night in, you can even serve it as a dip with crusty bread, veggie sticks, or low-carb crackers.