This mac and cheese tuna casserole is creamy, comforting, and practical for busy weeknights, combining tender macaroni, flaky tuna, sweet peas, and a rich cheese sauce under a crisp cheddar and French-fried onion topping.
When you want a filling dinner made mostly from pantry staples, this casserole makes the process wonderfully straightforward. Boxed macaroni and cheese provides a familiar creamy base, while condensed chicken soup gives the sauce extra body and helps keep the pasta moist as it bakes.
The combination of tuna, peas, and mild cheddar keeps the flavors simple and family-friendly. Adding the French-fried onions near the end is especially important because they stay much crunchier than they would if baked for the entire cooking time.
It is also a useful make-ahead meal for nights when you would rather assemble dinner early and bake it when everyone is ready to eat. Serve it straight from the baking dish with a simple vegetable or salad for a complete, low-effort meal.
Mac and Cheese Tuna Casserole Ingredients
Boxed macaroni and cheese: A 7.25-ounce dinner kit supplies both the macaroni and the cheese sauce mix, giving the casserole its familiar creamy base.
Chunk light tuna: Drain the tuna very thoroughly and separate it into flakes so it distributes evenly instead of forming large clumps throughout the pasta.
Sweet peas: Drained canned peas bring mild sweetness and a little color while pairing naturally with tuna and creamy pasta.
Condensed cream of chicken soup: Thickens the sauce and adds savory flavor while helping prevent the casserole from becoming dry in the oven.
Milk: Loosens the cheese sauce so it can coat the macaroni, peas, and tuna evenly.
Butter: Gives the packaged cheese sauce a smoother, richer consistency.
Mild cheddar cheese: Melts over the finished casserole and creates an additional cheesy layer without overwhelming the tuna.
French-fried onions: Provide the crunchy, savory topping that contrasts with the creamy macaroni underneath.
Nonstick cooking spray: Keeps the casserole from sticking to the baking dish and makes serving and cleanup easier.
Cooking Steps
STEP 1: Heat your oven to 350°F (175°C). Lightly coat a 9 × 13-inch baking dish with nonstick cooking spray, making sure the bottom and corners are covered.
STEP 2: Bring about 6 cups of water to a boil in a medium saucepan. Remove the macaroni from the dinner kit, setting the cheese packet aside. Cook the pasta for about 7 minutes, until tender but not overly soft. Drain it thoroughly, rinse briefly with cold water, and drain again.
STEP 3: Return the saucepan to the stove and melt the butter over medium heat. Stir in the milk and the reserved packaged cheese mix. Continue stirring until the powder has completely dissolved and the sauce looks smooth.
STEP 4: Add the condensed cream of chicken soup to the cheese mixture. Cook for approximately 3 minutes, stirring regularly, until everything is blended and warmed through. Avoid aggressively boiling the sauce; gentle heat is all you need.
STEP 5: Place the cooked macaroni in a large bowl with the well-drained peas and flaked tuna. Pour the warm cheese sauce over everything and fold gently until the pasta and filling are evenly coated. Transfer the mixture to your prepared baking dish and spread it into an even layer.
STEP 6: Bake the casserole uncovered for 30 minutes. Remove it from the oven and sprinkle the shredded cheddar evenly over the surface. Finish with an even layer of French-fried onions.
STEP 7: Return the dish to the oven for about 5 minutes, just long enough for the cheddar to melt and the onions to become hot and golden. For additional browning, you can broil the casserole for about 1 minute, but watch it continuously because the onion topping can darken very quickly.
What to Serve with Mac and Cheese Tuna Casserole
Because this tuna casserole is already creamy and substantial, lighter side dishes work particularly well alongside it.
- Simple green salad: Crisp lettuce, cucumber, and a tangy dressing provide a fresh contrast to the rich cheese sauce.
- Steamed green vegetables: Broccoli, green beans, or asparagus add freshness without competing with the casserole’s mild flavors.
- Roasted vegetables: Carrots, Brussels sprouts, or zucchini bring caramelized flavor and make the meal feel more complete.
Can I assemble the casserole ahead of time?
Yes. Prepare the macaroni mixture and transfer it to the baking dish, but leave off the shredded cheddar and French-fried onions. Cover and refrigerate until you are ready to bake.
When baking directly from the refrigerator, the casserole may need a little longer to heat completely through. Add the cheddar and onions only during the final few minutes so the topping remains crisp.
Why should I rinse the macaroni after cooking?
Rinsing stops the pasta from continuing to cook and removes some surface starch, which can help prevent the macaroni from becoming overly soft while the casserole bakes.
Because the pasta cooks again in the oven for about 35 minutes, you do not want it excessively tender before assembling the dish. Drain it especially well afterward so extra water does not thin the sauce.
Can I use a different condensed soup?
A similar creamy condensed soup can work, although it will change the flavor of the casserole. Condensed cream of mushroom is one common pairing with tuna because its savory flavor complements both the fish and cheese.
Whatever you use, keep the quantity close to the original 10.5-ounce can so the consistency of the sauce remains balanced.
How do I keep the French-fried onions crispy?
Do not add them when the casserole first goes into the oven. Bake the macaroni mixture by itself, then sprinkle the cheddar and French-fried onions over the top during the final 5 minutes.
That shorter baking time warms and browns the onions without giving them enough time to absorb too much moisture from the casserole.
How do I know when the casserole is ready?
The filling should be thoroughly hot, the sauce should look creamy around the pasta, and the cheese on top should be fully melted. The French-fried onions should also be lightly golden.
Remember that nearly all of the components are already cooked before assembly, so the baking stage is primarily about heating the casserole evenly and bringing the flavors together.
Helpful Tips
- Drain the tuna and peas thoroughly. Excess liquid can dilute the cheese sauce and make the finished casserole watery instead of creamy.
- Avoid overcooking the macaroni. It continues softening in the oven, so cook it only until tender during the initial boiling step.
- Watch closely if you broil the topping. French-fried onions can move from golden to burned quickly, so about 1 minute under the broiler is usually plenty.
Keeping Leftovers Fresh
Allow leftover mac and cheese tuna casserole to cool before transferring it to an airtight container or covering the baking dish securely. Refrigerate it promptly and use it within about 3 to 4 days.
For individual portions, reheating in the microwave is convenient. Add the casserole to a microwave-safe plate and heat in short intervals until it is hot throughout. If the pasta seems slightly dry after refrigeration, adding a small splash of milk before reheating can help restore some creaminess.
For larger portions, cover the casserole and warm it in a 350°F oven until heated through. Removing the cover during the final few minutes can help the topping regain some crispness, although French-fried onions will naturally soften somewhat during storage.
You can also freeze the casserole, preferably before adding the cheddar and French-fried onion topping. Wrap it securely and freeze for up to about 2 months for the best texture. Thaw it overnight in the refrigerator before reheating or baking, then add fresh cheddar and onions toward the end.
This mac and cheese tuna casserole is at its best when freshly baked, when the sauce is creamy and the onion topping is crisp, but its simple ingredients and reliable reheating make it equally useful for planned leftovers and make-ahead dinners.
Mac and Cheese Tuna Casserole
Ingredients
For the Casserole
- 1 can 5 oz chunk light tuna, thoroughly drained and separated into flakes
- ¾ cup milk
- Nonstick cooking spray as needed for coating the baking dish
- 1 can 15 oz sweet peas, drained well
- ¼ cup butter
- 1 can 10.5 oz condensed cream of chicken soup
- 1 box 7.25 oz macaroni and cheese dinner, including both the pasta and packaged cheese sauce mix
For the Topping
- 1⅓ cups French-fried onions
- 1 cup mildly flavored cheddar cheese shredded
Instructions
- Heat the oven to 350°F (175°C). Lightly coat the interior of a 9 × 13-inch baking dish with nonstick cooking spray.
- Pour 6 cups of water into a medium saucepan and bring it to a boil. Remove the macaroni from the dinner kit, reserving the cheese sauce packet for later.
- Add the macaroni to the boiling water and cook for 7 minutes, or until tender. Drain thoroughly, rinse the pasta with cold water, and drain once more.
- Using the same saucepan, melt ¼ cup butter over medium heat.
- Pour in ¾ cup milk and add the reserved cheese sauce mix from the macaroni and cheese package. Stir until the mixture becomes smooth and evenly combined.
- Blend in the condensed cream of chicken soup. Continue cooking and stirring for approximately 3 minutes, until the sauce is completely heated through and has a smooth consistency.
- Place the cooked macaroni in a large mixing bowl. Add the drained sweet peas and the drained, flaked tuna.
- Pour the warm cheese-and-soup mixture over the macaroni mixture. Gently fold everything together until the pasta, peas, and tuna are evenly coated.
- Transfer the mixture to the prepared 9 × 13-inch dish and spread it into an even layer.
- Place the casserole in the preheated oven and bake for 30 minutes.
- Remove the dish from the oven. Distribute the shredded mild cheddar evenly across the surface, then scatter the French-fried onions over the cheese.
- Return the casserole to the oven and bake for approximately 5 additional minutes, or until the cheddar has melted and the onions are golden brown.