When I want a cozy, crowd-pleasing side that also works as a meatless main, this Spinach Casserole is my go-to. It is creamy, cheesy, and perfectly golden on top with just the right spinach-to-sauce balance.
With make-ahead options and freezer friendliness, it is a weeknight win and a holiday hero.
Why You’ll Love This Spinach Casserole
- Comforting and creamy with a crisp, buttery topping that everyone loves.
- Uses pantry staples and flexible dairy options you already have.
- Make-ahead and freezer friendly for low-stress meals.
- Easy to adapt for gluten-free, vegetarian, or low-carb needs.
- Pairs beautifully with everything from roast chicken to salmon.
Spinach Casserole Ingredients & Substitutions
- Spinach: 2 boxes frozen chopped spinach (10 oz each), thawed and squeezed dry, or 2 lb fresh spinach, wilted, drained, and chopped. Fresh equals about 3 to 4 packed cups cooked.
- Butter and olive oil: 3 tbsp butter + 1 tbsp olive oil for richness and to sauté aromatics. Use ghee or plant butter as needed.
- Onion and garlic: 1 medium yellow onion (finely chopped) and 3 garlic cloves (minced) for savory depth. Shallots work too.
- Flour: 3 tbsp all-purpose flour to thicken the sauce. Use a 1:1 gluten-free flour blend to keep it GF.
- Milk or half-and-half: 1 1/2 cups whole milk or half-and-half. For lighter, use 2% milk. For dairy-free, use unsweetened cashew or oat milk.
- Cream cheese: 4 oz, softened, for extra silkiness. Swap with mascarpone or more sour cream, or omit for lighter texture.
- Sour cream or Greek yogurt: 1/2 cup for tang and body. Dairy-free yogurt works.
- Cheese: 1 cup shredded mozzarella or Gruyere, plus 1/2 cup grated Parmesan. Cheddar or fontina are tasty swaps.
- Eggs: 2, lightly beaten, to set the casserole. Omit if you prefer a looser scoopable casserole.
- Seasoning: 1 tsp kosher salt, 1/2 tsp black pepper, 1/4 tsp ground nutmeg, 1/4 tsp red pepper flakes, and 1/2 tsp lemon zest for brightness.
- Topping: 3/4 cup panko + 2 tbsp melted butter + 2 tbsp Parmesan. Use gluten-free panko, crushed pork rinds for low carb, or almond meal for a nutty option.
Step-by-Step Instructions to Make Spinach Casserole
Preheat and prep the dish
Heat oven to 375°F. Grease a 2-quart baking dish or a 9×9 inch pan with butter or nonstick spray.
Prep the spinach
If using frozen spinach, thaw completely and squeeze out every bit of moisture using a clean kitchen towel or a potato ricer. If using fresh spinach, sauté or steam until just wilted, then drain, chop, and squeeze dry. Excess moisture is the enemy of a creamy casserole.
Build the creamy base
Warm butter and olive oil in a large skillet over medium heat. Add onion with a pinch of salt and cook until soft and translucent, 5 to 7 minutes. Stir in garlic for 30 seconds. Sprinkle in flour and cook, stirring, 1 minute. Slowly whisk in milk, bring to a gentle simmer, and cook until thick enough to coat a spoon, 3 to 4 minutes.
Stir in the cheeses
Off the heat, whisk in cream cheese and sour cream until smooth. Stir in mozzarella and 1/4 cup Parmesan until melted. Season with salt, pepper, nutmeg, red pepper flakes, and lemon zest.
Combine and season the spinach
Fold the squeezed-dry spinach into the sauce. Taste and adjust seasoning. Stir in the beaten eggs until evenly combined.
Top and bake
Spread the mixture into the prepared dish. Toss panko with melted butter and remaining 1/4 cup Parmesan, then sprinkle over the top. Bake 20 to 25 minutes until bubbling at the edges and the topping is golden.
Rest and serve
Let the casserole rest 10 minutes so it sets cleanly for serving. The flavors bloom as it cools slightly.
Tips for Success
- Squeeze the spinach very dry. A potato ricer makes it effortless.
- Season in layers. Salt the onions, season the sauce, then taste again after adding spinach.
- Do not rush the thickening step. The sauce should lightly coat a spoon before you add cheese.
- A pinch of nutmeg is classic with leafy greens and dairy. It should be subtle, not pronounced.
- For an extra-crispy top, broil for 1 to 2 minutes at the end, watching closely.
Variations of Spinach Casserole
- Spinach Artichoke: Fold in 1 cup chopped marinated artichoke hearts.
- Mushroom and Spinach: Sauté 8 oz sliced cremini with the onion until browned.
- Bacon or Prosciutto: Add 1/2 cup chopped, crisped bacon or torn prosciutto.
- Spicy: Stir in 1 diced jalapeño or 1 tsp Calabrian chili paste.
- Lighter: Skip cream cheese and use 2% milk with Greek yogurt.
- Gluten-Free: Use GF flour and GF panko.
- Keto/Low Carb: Thicken with a slurry of 1 tsp xanthan gum or reduce the sauce longer, and skip the crumbs.
- Vegan: Use plant milk, vegan cream cheese, and vegan mozzarella and Parmesan. Omit eggs and thicken the sauce a bit more.
Serving Suggestions: What to Pair with Spinach Casserole
- Roast chicken, baked salmon, or seared steak for a balanced dinner.
- With a crisp salad and crusty bread for a cozy vegetarian meal.
- Alongside holiday mains like turkey or glazed ham.
- Brunch twist: serve with soft-scrambled eggs and smoked salmon.
Storage & Reheating Instructions
- Refrigerate: Cool completely, cover, and chill up to 4 days.
- Reheat: 350°F oven, covered, 15 to 20 minutes until hot; uncover for the last few minutes to re-crisp the topping. Microwave individual portions 60 to 90 seconds.
- Freeze: Wrap tightly and freeze up to 3 months. Thaw overnight in the fridge, then reheat at 350°F for 25 to 30 minutes. Broil briefly if the topping needs reviving.
Memories Made Around the Table
My grandma taught me the towel-squeeze trick after a holiday casserole came out watery. We remade it together the next day, and that golden, crunchy top with creamy spinach underneath became our little tradition. Simple food, big memories.
FAQs
Can I use fresh spinach instead of frozen?
Yes. Start with about 2 pounds fresh, wilt it, drain well, chop, and squeeze completely dry. Aim for roughly the same volume as two 10 oz boxes of frozen, fully squeezed.
How can I make this ahead?
Assemble up to the breadcrumb step, cover, and refrigerate up to 24 hours. Add the topping just before baking. You may need an extra 5 minutes in the oven when baking from cold.
How do I prevent a watery casserole?
Remove as much liquid as possible from the spinach, and make sure your sauce is nicely thick before adding the cheese. Rest the casserole 10 minutes after baking.
What cheese works best?
I love a blend of mozzarella for melt and Parmesan for savory depth. Gruyere, fontina, or sharp cheddar are delicious alternatives.
Final Thoughts
This Spinach Casserole checks every box: creamy, comforting, and beautifully adaptable. Make it once, and you will keep it in your back pocket for busy weeknights and special gatherings alike.
Spinach Casserole
Equipment
- 1 9x9 inch baking dish or a 2-quart baking dish
- 1 Large Skillet
- 1 Whisk
- 1 Potato ricer (optional, for squeezing spinach)
Ingredients
Spinach Casserole
- 2 boxes frozen chopped spinach 10 oz each, thawed and squeezed dry
- 2 lb fresh spinach wilted, drained, chopped, and squeezed dry (alternative to frozen)
- 3 tbsp butter
- 1 tbsp olive oil
- 1 yellow onion medium, finely chopped
- 3 cloves garlic minced
- 3 tbsp all-purpose flour
- 1.5 cups whole milk or half-and-half
- 4 oz cream cheese softened
- 0.5 cup sour cream or Greek yogurt
- 1 cup shredded mozzarella or Gruyere
- 0.5 cup Parmesan cheese grated, divided
- 2 eggs lightly beaten
- 1 tsp kosher salt
- 0.5 tsp black pepper
- 0.25 tsp ground nutmeg
- 0.25 tsp red pepper flakes
- 0.5 tsp lemon zest
Topping
- 0.75 cup panko breadcrumbs
- 2 tbsp butter melted
- 0.25 cup Parmesan cheese grated
Instructions
Preheat and prep the dish
- Heat oven to 375°F. Grease a 2-quart baking dish or a 9x9 inch pan with butter or nonstick spray.
Prep the spinach
- If using frozen spinach, thaw completely and squeeze out every bit of moisture using a clean kitchen towel or a potato ricer. If using fresh spinach, sauté or steam until just wilted, then drain, chop, and squeeze dry. Excess moisture is the enemy of a creamy casserole.
Build the creamy base
- Warm butter and olive oil in a large skillet over medium heat. Add onion with a pinch of salt and cook until soft and translucent, 5 to 7 minutes. Stir in garlic for 30 seconds. Sprinkle in flour and cook, stirring, 1 minute. Slowly whisk in milk, bring to a gentle simmer, and cook until thick enough to coat a spoon, 3 to 4 minutes.
Stir in the cheeses
- Off the heat, whisk in cream cheese and sour cream until smooth. Stir in mozzarella and 1/4 cup Parmesan until melted. Season with salt, pepper, nutmeg, red pepper flakes, and lemon zest.
Combine and season the spinach
- Fold the squeezed-dry spinach into the sauce. Taste and adjust seasoning. Stir in the beaten eggs until evenly combined.
Top and bake
- Spread the mixture into the prepared dish. Toss panko with melted butter and remaining 1/4 cup Parmesan, then sprinkle over the top. Bake 20 to 25 minutes until bubbling at the edges and the topping is golden.
Rest and serve
- Let the casserole rest 10 minutes so it sets cleanly for serving. The flavors bloom as it cools slightly.