Chicken and Spinach Casserole

Chicken and Spinach Casserole is a cozy, comforting dish that brings together tender chicken pieces, fresh spinach, and creamy cheese all baked to bubbly perfection. The combination of juicy chicken…

By Julia • February 28, 2026 • Reading time: 6 min

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Chicken and Spinach Casserole is a cozy, comforting dish that brings together tender chicken pieces, fresh spinach, and creamy cheese all baked to bubbly perfection. The combination of juicy chicken and the earthiness of spinach makes for a dish that feels both nourishing and satisfying, perfect for a family dinner or a laid-back weekend meal.

One thing I love about this casserole is how easy it is to prepare ahead of time. I often make it on a busy day and then pop it in the oven when I’m ready to eat. The cheese melts just right, and the spinach softens into the creamy sauce, making every bite a warm hug on your plate.

I like serving this with simple sides like crusty bread or a fresh salad to balance out the richness. It’s one of those meals that feels homey and special at the same time, and somehow it always brings everyone around the table with happy smiles. If you’re looking for a straightforward, wholesome dish that doesn’t require a lot of fuss, this casserole is a wonderful choice.

Key Ingredients & Substitutions

Chicken: Cooked chicken breast works best for tender bites. Rotisserie chicken or leftover cooked chicken works great too and saves time.

Spinach: Fresh spinach adds a bright, tender flavor. You can use frozen spinach if fresh is unavailable—just thaw and squeeze out excess water before using.

Cheese: Mozzarella melts well for a stretchy, creamy texture. Parmesan adds sharpness. Feel free to swap mozzarella with cheddar, Monterey Jack, or any good melting cheese.

Heavy Cream: Heavy cream makes the sauce rich and smooth. For a lighter dish, use whole milk, but the sauce may be thinner. Half-and-half is a good middle ground.

Garlic & Onion: These add depth and aroma to the sauce. Use fresh minced garlic and finely chopped onion for best flavor. You can reduce garlic if you prefer a milder taste.

How Do I Make a Smooth, Creamy Sauce Without Clumps?

Making the sauce starts with a roux—cooked flour and butter—that thickens the cream perfectly. Here’s how:

• Melt butter over medium heat, then add onions and garlic, cooking until soft but not browned.
• Sprinkle in the flour and stir constantly for about 1 minute to cook out the raw taste. This forms the roux.
• Slowly whisk in the cream or milk bit by bit—pouring all at once can cause lumps.
• Keep stirring as the mixture thickens; it should become creamy and smooth.
• If lumps form, whisk vigorously or strain the sauce before adding other ingredients.

Patience is key here. Stirring constantly and adding the liquid slowly helps you avoid clumps and makes the sauce silky and rich.

Equipment You’ll Need

• Large skillet – perfect for sautéing onions and making the creamy sauce all in one pan.
• Whisk – helps keep the sauce smooth and lump-free when you add the cream.
• Medium-sized casserole dish – roomy enough for the mixture to bake evenly and get golden on top.
• Knife and cutting board – for chopping chicken, garlic, onion, and parsley easily.
• Measuring cups and spoons – to get your cream, flour, and seasonings just right.

Flavor Variations & Add-Ins

• Swap chicken for cooked turkey or shredded rotisserie chicken for a quick twist with similar texture.
• Add mushrooms or sun-dried tomatoes for extra depth and a slightly tangy contrast.
• Try different cheeses like cheddar for sharper flavor or pepper jack for a touch of spice.
• Stir in red pepper flakes or a pinch of nutmeg to add warmth without overpowering the dish.

Chicken and Spinach Casserole

Ingredients You’ll Need:

Main Ingredients:

• 2 cups cooked chicken breast, cut into bite-sized pieces
• 4 cups fresh spinach leaves
• 2 cups shredded mozzarella cheese (or any melting cheese)
• 1 cup grated Parmesan cheese
• 2 cups heavy cream (or whole milk for lighter version)
• 2 cloves garlic, minced
• 1 small onion, finely chopped
• 2 tablespoons butter
• 2 tablespoons all-purpose flour
• 1 teaspoon dried thyme (optional)
• Salt and freshly ground black pepper to taste
• Fresh parsley, chopped (for garnish)
• Olive oil or cooking spray (for greasing the baking dish)

How Much Time Will You Need?

You’ll need about 10 minutes for preparation and about 25 minutes to bake the casserole. Overall, plan for around 35 minutes from start to finish to enjoy a warm, cheesy meal.

Step-by-Step Instructions:

1. Prepare the Oven and Dish:

Preheat your oven to 375°F (190°C). Lightly grease a medium-sized casserole dish with olive oil or cooking spray to prevent sticking.

2. Cook the Aromatics and Make the Sauce:

In a large skillet over medium heat, melt the butter. Add the chopped onion and minced garlic, cooking for 3-4 minutes until the onion is soft and fragrant. Stir in the flour and cook for another minute to form a roux, stirring constantly. Gradually whisk in the heavy cream, stirring until the sauce thickens to a creamy consistency.

3. Add Chicken and Spinach:

Mix in the cooked chicken pieces, fresh spinach, dried thyme (if using), salt, and pepper. Cook until the spinach wilts, about 3 minutes. Remove the skillet from heat and stir in half of the shredded mozzarella and all the Parmesan until melted and combined.

4. Assemble and Bake:

Transfer the mixture into your prepared casserole dish. Sprinkle the remaining mozzarella cheese evenly over the top. Bake in the preheated oven for 20-25 minutes, or until the cheese on top is golden brown and bubbly.

5. Garnish and Serve:

Let the casserole cool slightly before sprinkling with freshly chopped parsley. Serve warm and enjoy your creamy, cheesy Chicken and Spinach Casserole!

Can I Use Frozen Spinach Instead of Fresh?

Yes! Just make sure to thaw the frozen spinach fully and squeeze out any excess water before adding it to the casserole to avoid extra moisture.

Can I Substitute Milk for Heavy Cream?

Absolutely! Using whole milk will make the casserole lighter but slightly less creamy. You can also try half-and-half for a good balance of richness and lower fat.

How Do I Store Leftovers?

Keep leftovers in an airtight container in the fridge for up to 3 days. Reheat gently in the oven or microwave until warmed through.

Can I Make This Casserole Ahead of Time?

Yes, you can prepare the casserole up to the baking step, cover it, and refrigerate for up to 24 hours. When ready, bake as directed, adding a few extra minutes if baking from cold.