Comfort food that feels like a warm hug — that’s what this Tuna Rice Casserole delivers. With tender, fluffy rice, creamy egg-and-milk binder, tangy mustard, rich mayonnaise, and melty mozzarella, it’s a weeknight winner that stretches to feed a crowd. The recipe uses pantry-friendly cans of tuna, simple dairy and pantry staples, and comes together in a single casserole dish. Below you’ll find a friendly narrative about why this dish works, serving tips, and a clear, step-by-step recipe so your kitchen time is relaxed and productive. Let’s dive in.

Why you’ll love this Tuna Rice Casserole

This Tuna Rice Casserole is the kind of recipe that famously makes more than the sum of its parts. The rice absorbs the flavorful custard made from almond milk and eggs, which keeps every forkful moist and satisfying. Stone ground mustard punches through the richness with a bright tang, while the mayonnaise adds a rounded, velvety texture that makes the casserole feel indulgent without being heavy. Three cans of tuna provide hearty protein and a mild ocean flavor that pairs beautifully with melted mozzarella on top. Because the casserole bakes until bubbly and golden, it has comfort-food appeal and an inviting aroma that fills the house.

Ingredients

Use these measured ingredients exactly as listed for consistent results.

2 cups uncooked white rice
1 2/3 cups unsweetened almond milk*
2 large eggs
3 Tbsp avocado oil mayonnaise**
2 Tbsp stone ground mustard
3 (6-oz) cans tuna, drained
3 cups mozzarella cheese, divided***

* Unsweetened almond milk keeps the casserole lighter in flavor and allows the other savory ingredients to shine.

** Avocado oil mayonnaise provides a neutral-tasting, smooth fat that helps bind the mixture and contributes to a tender bake.

*** Reserve about 1 cup of the mozzarella for a finishing layer so the top gets beautifully melty and golden.

Equipment

9×13-inch baking dish
Large saucepan with lid (for rice)
Mixing bowl and whisk
Large spoon or spatula
Cheese grater (if not using pre-shredded mozzarella)

Prep and timing

Total time: about 1 hour 10 minutes (includes rice cooking and baking).

Active prep: 20–25 minutes
Bake time: 35–40 minutes

Step-by-step Instructions

The following directions rewrite the original steps into clear, sequential actions. Quantities match the ingredient list exactly. Follow these steps to produce a consistent, delicious Tuna Rice Casserole.

Preheat and prepare dish: Preheat your oven to 375°F (190°C). Lightly grease a 9×13-inch baking dish with a bit of oil or cooking spray and set it aside.
Cook the rice: Rinse 2 cups uncooked white rice briefly under cold water until the water runs mostly clear to remove excess starch. In a large saucepan, combine the rinsed rice with the appropriate amount of water according to the rice package directions (usually about 4 cups of water for 2 cups of white rice), bring to a boil, then reduce the heat to low, cover, and simmer until all the water is absorbed and the rice is tender—about 15–20 minutes depending on your rice variety. Once cooked, fluff the rice with a fork and allow it to cool slightly for a few minutes so it’s warm but not steaming.
Mix the binder: In a medium mixing bowl, whisk together 1 2/3 cups unsweetened almond milk and 2 large eggs until smooth and slightly frothy. Add 3 tablespoons avocado oil mayonnaise and 2 tablespoons stone ground mustard; continue whisking until the mixture is homogenous and well combined.
Combine tuna and rice: Drain the 3 (6-oz) cans tuna thoroughly to remove excess liquid. Break the tuna into flakes with a fork. Add the drained tuna to the warm rice in the saucepan or a large bowl, then pour in the egg-and-milk mixture. Stir gently but thoroughly to distribute the tuna and binder throughout the rice.
Add cheese and fold: Measure out 3 cups mozzarella cheese and reserve approximately 1 cup for the topping. Stir the remaining 2 cups of mozzarella into the rice and tuna mixture so the cheese is evenly incorporated. The mixture should be cohesive and slightly saucy from the milk-and-egg binder.
Transfer to baking dish: Spoon the combined mixture into the prepared 9×13-inch baking dish, spreading it into an even layer. Smooth the top gently with the back of a spoon or spatula.
Top with mozzarella: Sprinkle the reserved 1 cup of mozzarella evenly over the surface of the casserole for a glossy, melty top.
Bake until set and golden: Place the baking dish in the preheated oven and bake for 35–40 minutes, or until the casserole is set in the center and the cheese on top is melted and beginning to turn golden. If the top browns too quickly before the casserole is fully set, loosely tent the dish with foil and continue baking until done.
Rest before serving: When the casserole is baked through, remove it from the oven and let it rest for 8–10 minutes. This resting time allows the custard to firm up slightly and makes slicing easier.
Serve: Cut into squares and serve warm. This Tuna Rice Casserole pairs nicely with a simple green salad or steamed vegetables for contrast.

Troubleshooting and tips

Rice texture: If your rice turns out too al dente after tasting during prep, allow a couple extra minutes of covered simmering. Overly soft rice can make the casserole too dense once baked, so aim for just-tender grains.
Moisture balance: The egg-and-milk binder creates custard while the casserole bakes. If you accidentally add more liquid items later (like extra mayo or drained tuna that still has moisture), reduce added liquid slightly to prevent a watery dish.
Even baking: Use a 9×13-inch pan to ensure the casserole bakes through in the suggested time. A deeper dish will require longer baking; check for set center and an internal temperature around 165°F (74°C).
Cheese variations: Mozzarella gives a mild, melty top. For added flavor, mix half mozzarella and half mild cheddar for a sharper taste, keeping total cheese at 3 cups.

Make-ahead and storage

This casserole is a great candidate for make-ahead cooking. Assemble the casserole in the baking dish up to the point of adding the final cup of mozzarella. Cover tightly with foil or plastic wrap and refrigerate for up to 24 hours. When ready to bake, remove from the fridge, top with the reserved mozzarella, and add a few extra minutes to the baking time if it’s chilled. Leftovers keep well for 3–4 days in a covered container in the refrigerator. Reheat individual portions in the microwave until heated through, or rewarm an entire dish in a 350°F (175°C) oven until bubbling.

Serving suggestions

Because this Tuna Rice Casserole is rich and creamy, it benefits from something fresh and bright on the plate. Try:

A crisp green salad dressed simply with lemon and olive oil.
Steamed green beans tossed with a squeeze of lemon.
A quick cucumber and tomato salad tossed with chopped parsley and a light vinaigrette.
Pickled vegetables for contrast if you enjoy a tangy bite alongside the creamy casserole.

Flavor variations

Want to play with flavors? Here are a few simple swaps that work without changing any amounts:

Add 1/2 cup frozen peas or corn to the rice mixture for a sprinkle of color and subtle sweetness. Fold them in after the rice and tuna are combined, before adding the cheese.
Stir in a teaspoon or two of dried herbs like dill or parsley into the milk-and-egg mixture for an herb-forward profile.
For a smoky note, add a pinch of smoked paprika to the binder mixture. It pairs well with tuna and adds depth to the finished casserole.

Why the ratios matter

This recipe balances starch, protein, and a creamy binder to achieve a casserole that holds together without being gluey or dry. Two cups of uncooked rice yield a substantial base so the tuna and cheese aren’t overwhelming. The 1 2/3 cups of almond milk with two eggs create enough custard to moisten the rice and help the casserole set as it bakes. Three tablespoons of mayonnaise lend richness and help the dish slice cleanly, while 2 tablespoons of stone ground mustard cut through the richness with brightness. Three cans of tuna ensure every bite is satisfying, and 3 cups of mozzarella bring the gooey, cheesy appeal we all want from a casserole.

Final thoughts

This Tuna Rice Casserole is proof that humble ingredients can become something comforting and memorable. It’s forgiving enough for cooks of all levels and makes an excellent option for family dinners, potlucks, or a simple meal to stretch through the week. Keep the recipe on your regular rotation and don’t be afraid to add a few mix-ins from the pantry or fridge — this dish is a perfect canvas for creativity.

Enjoy the warm, cheesy slices straight from the oven or pack leftovers for a satisfying lunch the next day. Happy baking and hearty eating!