Our spinach gratin recipe is how spinach was meant to be consumed—with lots of cheese! We perfected this recipe so it’s not ‘soupy’ like au gratin dishes you may have tasted in the past. In fact, we added just enough sauce to bind and flavor the spinach and used a nice, high-quality Monterey Jack or Gruyere cheese.
Don’t be fooled by the cheese, however, because our recipe contains nearly three pounds of leafy greens, making it a dense and hearty side dish. Sometimes our recipes are picked through but not totally consumed—but this time, there wasn’t a sliver of spinach or even a singlet of melted cheese left stuck to the pan. It’s that good.
Our spinach gratin is perfect for every day dinners, a welcome holiday side dish and perfect for company. It’s a recipe that pairs well with just about anything, and while it’s listed under ‘sides,’ we’d be more than happy to eat this as a main course!
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Spinach Gratin Recipe Tips:
- Be sure to squeeze as much liquid as possible from the frozen spinach—the successful outcome of the dish depends on removing as much water as possible! A cheesecloth makes this super easy (paper towels can tend to disintegrate with all the extra moisture.)
- You can also use fresh spinach in this recipe, but you’ll need quite a bit. You’ll want to substitute 1 – 1.5lbs of fresh spinach for every 10oz bag of frozen – so 5 – 7lbs of fresh spinach for this recipe. Cook it down in a pan and then add it in at the same spot as the frozen spinach in the recipe.
- Not a fan of the cheeses we use? Swap in the melty ones that you prefer.
Spinach Gratin Recipe
- 3 Tbsp unsalted butter
- 1 large yellow onion, finely diced
- 1 clove garlic, minced
- 1/4 cup all-purpose flour
- 2 1/2 cups milk
- 2 tsp kosher salt
- 1/8 tsp nutmeg
- 5 10 oz boxes spinach, chopped, defrosted
- 1/2 cup Parmesan cheese, grated
- 1/2 tsp pepper
- 1/2 cup Monterey Jack cheese, or Gruyere cheese, shredded
- Preheat oven to 400 degrees, lightly coat a 2-qt casserole dish with cooking spray and set aside. Place a large skillet over medium heat then melt butter. Add onions and cook 3–4 minutes until translucent. Add garlic then cook 1 additional minute.
- Add flour then cook, stirring constantly for 1 additional minute. Add milk, salt and nutmeg then stir until combined. Bring liquid to a bubble then reduce heat to low and simmer for 10 minutes, stirring frequently to prevent scorching.
- Squeeze as much liquid as possible from the spinach—the successful outcome of the dish depends on removing as much water as possible! Add spinach and Parmesan cheese to sauce and stir until completely combined. Taste and season with additional salt and pepper if necessary.
- Transfer to prepared baking dish and sprinkle with Monterey Jack or Gruyere cheese. Bake for 28–30 minutes or until cheese becomes golden and dish is hot and bubbly.
Can this be frozen?
I loved this recipe. It was a great side dish for Thanksgiving. This recipe is a keeper. ❤️
Got rave reviews on this at Thanksgiving dinner!
Will make again.
This meal was the favorite of our Thanksgiving meal. Everyone loved it!
How much fresh spinach should I use?
I made it a day ahead to save time but I had to taste it. So good! I think it’ll be a hit as a Thanksgiving side dish.
I’d like to use fresh spinach. How much should I use?
How much spinach should I use if I want to use fresh spinach?