Description

Craving a rich, comforting side dish that elevates humble spinach to star status? Spinach Gratin, inspired by Ina Garten’s recipe, combines creamy spinach with a cheesy, golden topping for a crowd-pleasing addition to any meal.

Ingredients

Scale

Spinach Gratin uses pantry staples and frozen spinach for a rich, flavorful result. Here’s what you’ll need for 8 servings:

4 tablespoons (½ stick) unsalted butter: Sautés onions and forms the sauce base.
4 cups chopped yellow onions (2 large): Adds sweet, savory depth.
¼ cup all-purpose flour: Thickens the cream sauce.
¼ teaspoon grated nutmeg: Provides warm, earthy flavor.
1 cup heavy cream: Creates a rich, velvety texture.
2 cups milk: Lightens the sauce while keeping it creamy.
3 pounds frozen chopped spinach, defrosted (5 (10-ounce) packages): The hearty, green base.
1 cup freshly grated Parmesan cheese: Adds nutty, savory flavor.
1 tablespoon kosher salt: Seasons the dish.
½ teaspoon freshly ground black pepper: Adds mild spice.
½ cup grated Gruyere cheese: Forms a bubbly, golden topping.

Why These Ingredients Matter

Spinach: Frozen, chopped spinach offers convenience and a hearty texture.
Cream and Milk: Create a luxurious, creamy sauce.
Parmesan and Gruyere: Add savory, cheesy richness and a golden crust.
Nutmeg: Enhances the dish with a subtle, warm spice.

Substitutions and Variations

Spinach: Use fresh spinach (about 4 pounds, cooked, chopped, and drained) or frozen kale.
Butter: Swap with plant-based butter for vegan or olive oil for a lighter sauté.
Flour: Use gluten-free 1:1 flour for gluten-free.
Heavy Cream: Replace with half-and-half for a lighter sauce or plant-based cream for vegan.
Milk: Use whole milk, 2%, or plant-based milk (e.g., oat or soy).
Parmesan: Substitute with Pecorino Romano or nutritional yeast for vegan.
Gruyere: Swap with Swiss, Fontina, or extra Parmesan; use vegan cheese for vegan.
Vegan Option: Use plant-based butter, cream, milk, and cheeses (or nutritional yeast).
Gluten-Free: Use gluten-free flour; ensure all ingredients are gluten-free.
Flavor Variations:
- Mushroom Spinach Gratin: Add 1 cup sautéed sliced mushrooms to the spinach.
- Bacon Spinach Gratin: Mix in 4 slices cooked, crumbled bacon.
- Spicy Spinach Gratin: Add ¼ teaspoon red pepper flakes with the nutmeg.
- Artichoke Spinach Gratin: Stir in 1 cup chopped canned artichoke hearts.
- Herb Spinach Gratin: Add 1 tablespoon chopped fresh thyme or rosemary.

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Instructions

Step 1: Gather and Prep

Gather all ingredients: 4 tablespoons butter, 4 cups chopped yellow onions, ¼ cup flour, ¼ teaspoon nutmeg, 1 cup heavy cream, 2 cups milk, 3 pounds frozen spinach (defrosted), 1 cup Parmesan, 1 tablespoon kosher salt, ½ teaspoon black pepper, ½ cup Gruyere.
Defrost 5 (10-ounce) packages of frozen spinach in the refrigerator overnight or in the microwave (per package instructions).
Chop 2 large yellow onions (about 4 cups).
Grate Parmesan and Gruyere cheeses.

Tip: Squeeze spinach thoroughly in a clean kitchen towel to remove excess liquid for a non-watery gratin.

Step 2: Cook the Onions

Melt 4 tablespoons butter in a heavy-bottomed sauté pan over medium heat.
Add 4 cups chopped onions and sauté until translucent, about 15 minutes.

Tip: Stir occasionally to prevent browning; cook until soft for a sweet, mellow flavor.

Step 3: Make the Cream Sauce

Add ¼ cup flour and ¼ teaspoon grated nutmeg to the onions; cook, stirring, for 2 minutes to form a roux.
Add 1 cup heavy cream and 2 cups milk; cook, stirring, until thickened, about 3-5 minutes.

Tip: Whisk constantly to avoid lumps; the sauce should coat the back of a spoon.

Step 4: Combine with Spinach

Squeeze as much liquid as possible from the defrosted spinach.
Add spinach to the cream sauce along with ½ cup grated Parmesan; mix well.
Season with 1 tablespoon kosher salt and ½ teaspoon black pepper, adjusting to taste.

Tip: Mix thoroughly to evenly distribute the sauce; taste and adjust seasoning if needed.

Step 5: Assemble and Bake

Preheat the oven to 425°F (218°C).
Transfer the spinach mixture to a 3-quart baking dish (or 9×13-inch dish).
Sprinkle with the remaining ½ cup Parmesan and ½ cup grated Gruyere.
Bake for 20 minutes, until hot, bubbly, and golden on top.

Tip: Spread the mixture evenly; check at 15 minutes to avoid over-browning the cheese.

Step 6: Serve

Serve hot, about ¾-1 cup per serving.
Pair with holiday mains like deep-fried turkey, herb-roasted turkey breast, or sides like creamy garlic mashed potatoes.

Tip: Let rest for 5 minutes for easier serving; garnish with extra Parmesan or parsley for flair.