Easy Make-Ahead Spinach Gratin is a spinach side dish recipe for holiday meals, with frozen chopped spinach stirred into a classic Mornay sauce made with lightly browned onions, then topped with Gruyère and freshly grated Parmesan. If you're looking for a spinach au gratin or spinach gratin recipe you can assemble ahead of time, this one fits.
Short answer: Spinach gratin is a creamy, cheese-topped baked side dish that serves 6 and bakes in about 20 minutes at 425°F.
Jump to:
Quick Look at the Recipe
- Prep time: 25 minutes
- Cook time: 15 minutes
- Servings: 6, in a 2-quart casserole dish
- Difficulty level: Easy
- Make-ahead friendly: Yes. Assemble up to a day ahead, cover, and refrigerate. When baking cold from the refrigerator, add 10-15 minutes to the normal 20-minute bake at 425°F (about 30-35 minutes total), or until hot and bubbly.
- Leftover friendly: Yes
- Key tip: Squeeze as much liquid as possible from the thawed spinach for a creamy gratin.
Ingredients: Here's What You'll Need
- The Vegetables: I like to use frozen spinach for this amazing dish rather than fresh spinach, and I add onion for extra flavor.
- Cheeses: I used a combination of Parmesan cheese and Gruyère cheese in this recipe.
- Mornay Sauce: For the Mornay sauce, I used unsalted butter, all-purpose flour, milk, Kosher salt, pepper, and freshly grated nutmeg.
Here's How to Make This Delicious Spinach Gratin
- Initial prep: Preheat the oven to 425°F, spray a 2-quart casserole dish with nonstick spray, and set it aside.
- Squeeze the spinach: Start by squeezing as much liquid as possible from thawed frozen spinach by hand. Then, place the spinach in a double layer of paper towels and squeeze out the remaining liquid.
- Cook the onions: Melt the butter in a large skillet over medium heat for the sauce. Add the onions and sauté until lightly browned. This takes about 15 minutes.
- Cook the flour: Once the onions are lightly browned, add the flour, salt, pepper, and nutmeg to the skillet. Stir to combine and let the mixture cook for about 2 minutes to remove the raw flour taste.
- Add the milk: Then, add the milk and cook the sauce until it is bubbly and thickened.
- Add the Parmesan: Once the sauce is thickened and bubbly, add freshly grated Parmesan cheese; stir until the cheese is melted.
- Add the spinach: Finally, add the spinach and stir everything together until all of the ingredients are well incorporated.
Here's How to Finish the Spinach Gratin
Transfer the Spinach Gratin mixture to a casserole dish sprayed with nonstick spray.
Then, sprinkle on shredded Gruyère cheese and more freshly grated Parmesan cheese.
One of the nice things about this dish is that it can be made ahead of time up to this point, covered, and refrigerated.
Bake the spinach gratin in a preheated 425°F oven for about 20 minutes, or until hot and bubbly. If baking cold from the refrigerator, add 10-15 minutes (about 30-35 minutes total), or until hot and bubbly.
Talk about good! The spinach gratin was perfectly seasoned and full of cheesy goodness. In other words, it was absolutely delicious.
This cheesy spinach gratin is a great recipe to make to grace your holiday table or everyday table for that matter. Yum!
In Case You Were Wondering
A gratin is a dish that is usually made with a creamy sauce and topped with a layer of cheese or breadcrumbs.
Spinach gratin is a versatile dish that goes well with many main courses, such as roasted chicken, baked fish, grilled pork, or steak.
You can assemble spinach gratin up to a day ahead, cover it, and refrigerate it until you are ready to bake. When baking cold from the refrigerator, add 10-15 minutes to the normal 20-minute bake at 425°F (about 30-35 minutes total), or until hot and bubbly.
Spinach gratin will keep in the refrigerator for up to 3-4 days. Store it in an airtight container to keep it fresh.
Spinach gratin can be frozen. Just be sure to wrap it tightly in plastic wrap or foil and then place it in an airtight container or freezer bag. It will keep in the freezer for up to 2-3 months. To reheat, thaw it in the refrigerator overnight and then bake it in the oven until heated through.
PudgeFactor's Test Kitchen Tips
- The nutmeg added to the Mornay sauce provides a subtle enhancement to the sauce. I like to use fresh nutmeg. However, you can also use ground nutmeg in this dish.
- Either whole milk or 2% milk will work fine in this recipe for the Mornay sauce.
- One of the beauties of this dish is that you can prepare it up to a day in advance. Cover the casserole dish with aluminum foil and refrigerate it. When baking cold from the refrigerator, add 10-15 minutes to the normal 20-minute bake at 425°F (about 30-35 minutes total), or until hot and bubbly.
- The leftovers are as good, if not better. I generally heat the leftovers for several minutes in the microwave.
Other Delicious Spinach Dishes
If you like spinach, you should definitely try these other amazing dishes with spinach as the star:
Did you make this recipe? We'd love to know how it turned out! Leave a review below. Then, share a picture on Instagram and tag @pudgefactor so we can see it.
Don't forget to follow us on Pinterest, Facebook, YouTube, Flipboard, and Instagram.
Thank you so much for visiting PudgeFactor. We hope you'll come back!
Recipe
Want to Save This Recipe?
Enter your email & I'll send it to your inbox. Plus, enjoy weekly doses of culinary inspiration as a bonus!
By submitting this form, you consent to receive emails from Pudge Factor.
Easy Make-Ahead Spinach Gratin
Ingredients
- 24 ounce Package (680 grams) frozen chopped spinach, thawed
- 2 Tablespoons (1 ounce, 28 grams) unsalted butter
- 2 cups (11.3 ounces, 320 grams) Finely chopped onion (1 large onion)
- 2 Tablespoons all-purpose flour
- 1 teaspoon Kosher salt
- ¼ teaspoon freshly ground black pepper
- ⅛ teaspoon freshly grated nutmeg (See Tip 1)
- 1 ½ cups (12 ounces, 340 grams) milk (See Tip 2)
- ½ cup (2 ounces, 57 grams) freshly grated Parmesan cheese, divided
- ½ cup (2 ounces, 57 grams) shredded Gruyère cheese
Instructions
- Preheat the oven to 425°F. Spray a 2-quart casserole dish with non-stick spray. Set aside.
- By the handful, squeeze as much water as possible from the spinach. Repeat with paper towels. Set aside.
- Melt the butter in a large skillet over medium heat. Add the onions and sauté until lightly browned, about 15 minutes. Add the flour, salt, pepper, and nutmeg. Cook, stirring, for 2 more minutes. Add the milk and cook until thickened. Add ¼ cup of grated Parmesan cheese. Stir until melted. Add the spinach; mix well.
- Transfer the spinach mixture to the prepared casserole dish. Top with Gruyère cheese and the remaining Parmesan cheese. May be prepared in advance up to this point. (See Tip 3)
- Bake in a preheated 425°F oven for about 20 minutes, or until hot and bubbly. (See Tip 4)
- Yield: 6 servings. (See Tip 5)
Video
Tips/Notes
- I like to use fresh nutmeg. However, you can also use ground nutmeg in this dish.
- I used whole milk, but feel free to use 2% milk.
- You can prepare this up to a day in advance. Cover the casserole dish with aluminum foil and refrigerate.
- When baking cold from the refrigerator, add 10-15 minutes to the normal 20-minute bake at 425°F (about 30-35 minutes total), or until hot and bubbly.
- The leftovers are as good, if not better. I usually just heat the leftovers in the microwave for several minutes.
Anonymous says
I added a little bit of extra cheese but overall a delicious recipe!