Prep: 20 mins

Cook: 40 mins

Servings: 6

Imagine a cozy casserole that brings the sea to your dinner table, a dish that feels both indulgent and comforting. This Creamy Tuna Spinach Casserole blends flaky tuna, tender spinach, and a velvety cheese sauce into a golden‑browned bake that will have everyone reaching for seconds.

What makes it special is the balance between rich, creamy texture and bright, vegetal notes. The sauce is thickened with a touch of flour and enriched with milk and cheddar, while the spinach adds a pop of color and a subtle earthiness that lifts the whole dish.

Busy families, college students, and anyone craving a quick yet satisfying dinner will love this recipe. It’s perfect for weeknight meals, potlucks, or even a simple Sunday supper when you want something hearty without the fuss.

The process is straightforward: sauté aromatics, combine tuna and spinach, stir in the creamy sauce, then bake until bubbly and lightly crisp on top. In under an hour you’ll have a one‑dish wonder that fills the kitchen with an irresistible aroma.

Why You'll Love This Recipe

One‑Pan Simplicity: All the components are assembled in a single baking dish, so cleanup is minimal and you can focus on flavor, not dishes.

Family‑Friendly Comfort: The creamy sauce and mild tuna flavor appeal to both kids and adults, making it a crowd‑pleaser at any table.

Nutritious Boost: Spinach adds iron, calcium, and vitamins, while tuna supplies lean protein and omega‑3 fatty acids for a balanced meal.

Quick Weeknight Solution: With only 20 minutes of prep and 40 minutes of bake time, it fits perfectly into a busy schedule without sacrificing taste.

Ingredients

The heart of this casserole is a harmonious trio: high‑quality canned tuna, fresh baby spinach, and a rich cheese‑based sauce. The tuna provides protein and a subtle briny taste, while the spinach brings a fresh, slightly bitter contrast that prevents the dish from feeling heavy. The sauce, built on butter, flour, milk, and cheddar, binds everything together with a silky mouthfeel and a golden crust.

Main Ingredients

2 (5‑oz) cans tuna in water, drained
4 cups fresh baby spinach, roughly chopped
1 cup uncooked elbow macaroni or small pasta shells
1 cup shredded sharp cheddar cheese

Sauce Components

3 tablespoons unsalted butter
3 tablespoons all‑purpose flour
2 cups whole milk, warmed
½ teaspoon Dijon mustard

Seasonings & Toppings

½ teaspoon garlic powder
¼ teaspoon smoked paprika
Salt and freshly ground black pepper, to taste
¼ cup panko breadcrumbs (optional, for topping)

Each ingredient plays a purpose: the butter and flour create a roux that thickens the sauce, while the milk adds silkiness. Dijon mustard lifts the flavor with a subtle tang, and the cheddar delivers a sharp, melty finish. The breadcrumbs, if used, give a light crunch that contrasts with the creamy interior, turning a simple casserole into a textural delight.

Step-by-Step Instructions

Preparing the Pasta & Spinach

Bring a large pot of salted water to a boil. Add the elbow macaroni and cook according to package instructions until al dente, usually 8‑9 minutes. Drain and set aside. While the pasta cooks, rinse the spinach under cold water, spin dry, and roughly chop. This step ensures the greens wilt quickly later without releasing excess water.

Making the Creamy Base

Build the Roux. In a medium saucepan over medium heat, melt the butter until foamy. Sprinkle the flour over the butter and whisk continuously for 2‑3 minutes until the mixture turns a light golden color. This cooking eliminates the raw flour taste and forms the foundation for a smooth sauce.
Incorporate Milk. Gradually pour the warmed milk into the roux while whisking to prevent lumps. Continue whisking until the sauce thickens, about 4‑5 minutes, and coats the back of a spoon. The gradual addition ensures a silky texture without graininess.
Season & Enrich. Stir in Dijon mustard, garlic powder, smoked paprika, salt, and pepper. Add half of the shredded cheddar and let it melt completely, creating a glossy, cheesy sauce. The mustard adds a subtle zing that balances the richness.

Combining All Components

Fold in Tuna & Spinach. Add the drained tuna, chopped spinach, and cooked pasta to the sauce. Gently stir until everything is evenly coated. The residual heat will wilt the spinach just enough to retain its vibrant green color.
Transfer to Baking Dish. Lightly grease a 9‑x‑13‑inch casserole dish. Pour the mixture in, spreading it into an even layer. Sprinkle the remaining cheddar over the top, followed by panko breadcrumbs if you desire a crunchy crust.
Bake to Perfection. Preheat the oven to 375°F (190°C). Place the casserole in the center rack and bake for 20‑25 minutes, or until the top is golden and the sauce is bubbling around the edges. The breadcrumbs, when used, should turn a deep amber.

Finishing Touches

Remove the casserole from the oven and let it rest for 5 minutes. Resting allows the sauce to set, making slicing easier and preserving the creamy interior. Garnish with a sprinkle of fresh chopped parsley or a light drizzle of extra‑virgin olive oil for a glossy finish. Serve hot and enjoy the comforting blend of flavors.

Tips & Tricks

Perfecting the Recipe

Dry Tuna First. Pat the canned tuna with paper towels before adding it. Removing excess moisture prevents a watery casserole.

Use Fresh Spinach. Fresh leaves wilt quickly and keep a bright color, whereas frozen spinach can make the sauce soggy.

Don’t Over‑Bake. Keep an eye on the crust; once it’s golden, the interior is already hot and set.

Flavor Enhancements

Add a splash of dry white wine to the sauce before the milk for a subtle depth. A pinch of nutmeg pairs beautifully with the cheese, and a teaspoon of capers brings a briny pop that mirrors the tuna’s oceanic flavor.

Common Mistakes to Avoid

Avoid stirring the sauce too aggressively once the cheese melts; this can cause the sauce to separate. Also, never skip the resting time—cutting too early releases the creamy interior onto the plate, making it look soupy.

Pro Tips

Toast the Breadcrumbs. Lightly toast panko in a skillet with a drizzle of butter before sprinkling on top for extra crunch.

Use a Hand‑Mixer for the Roux. A whisk works, but a hand‑mixer speeds up the process and guarantees a lump‑free base.

Finish with Fresh Herbs. A handful of chopped chives or parsley added just before serving brightens the dish and adds a fresh aroma.

Adjust Consistency. If the sauce seems thick while mixing, whisk in an extra ¼ cup of warm milk to reach a silky pourable texture.

Variations

Ingredient Swaps

Swap the tuna for canned salmon or cooked shredded chicken for a different protein profile. Replace the cheddar with Gruyère or mozzarella for a milder melt. If you enjoy a bit of heat, stir in a chopped jalapeño or a dash of cayenne pepper with the seasonings.

Dietary Adjustments

For a gluten‑free version, use a gluten‑free flour blend for the roux and ensure the breadcrumbs are gluten‑free. Dairy‑free diners can replace butter with olive oil, milk with almond or oat milk, and cheddar with a plant‑based cheese that melts well. To keep it low‑carb, substitute the pasta with cauliflower rice or spiralized zucchini.

Serving Suggestions

Serve the casserole alongside a crisp green salad tossed with lemon vinaigrette, or pair it with buttery garlic bread for extra soak‑up power. For a lighter plate, add a side of roasted cherry tomatoes or a simple cucumber‑dill salad that cuts through the richness.

Storage Info

Leftover Storage

Allow the casserole to cool to room temperature, then transfer portions into airtight containers. Refrigerate for up to 4 days. For longer keeping, place the cooled dish in a freezer‑safe container, cover tightly with plastic wrap and foil, and freeze for up to 3 months. Label with date for easy reference.

Reheating Instructions

Reheat leftovers in a preheated 350°F oven, covered with foil, for 15‑20 minutes until warmed through; uncover for the last 5 minutes to crisp the topping. In a microwave, place a serving in a microwave‑safe dish, add a splash of milk, cover loosely, and heat on medium power for 2‑3 minutes, stirring halfway.

Frequently Asked Questions

Absolutely. Assemble the casserole up to the point of adding the breadcrumb topping, then cover and refrigerate for up to 24 hours. When ready, add the breadcrumbs and bake as directed. This makes a stress‑free weeknight dinner or a potluck contribution.

Frozen spinach works fine; just be sure to thaw it completely, squeeze out as much moisture as possible, and pat dry. This prevents a watery sauce. You may need to add a tablespoon more flour to the roux if the mixture seems thin after adding the milk.

Yes. Cooked quinoa, farro, or brown rice can replace the elbow macaroni for a heartier texture. Adjust the liquid slightly—grains absorb more moisture, so add an extra ¼ cup of milk to keep the sauce creamy.

Choose low‑sodium canned tuna and use unsalted butter. Reduce added salt, and rely on the natural flavor of the cheese and a splash of lemon juice for brightness. This keeps the dish flavorful without excess sodium.

This Creamy Tuna Spinach Casserole brings together pantry staples and fresh greens for a comforting, protein‑packed dinner that’s ready in under an hour. We’ve covered everything—from selecting the right tuna to mastering a lump‑free sauce and adding a crunchy topping. Feel free to swap ingredients, adjust seasonings, or personalize the garnish—cooking is your canvas. Serve it hot, share it with loved ones, and enjoy the cozy satisfaction of a truly homemade classic.