One-Pot Crockpot Tuna Casserole

Here is my go-to crockpot tuna casserole recipe, with tender egg noodles, creamy sauce, sweet peas, and that classic comfort food taste that brings back childhood memories.

This tuna casserole is a lifesaver on busy weeknights when I need something easy but filling for the family. I love that I can just dump everything in the crockpot and let it do all the work while I help with homework or catch up on laundry.

What Kind of Tuna Should I Use?

For this crockpot casserole, you’ll want to stick with canned tuna since it holds up well during the long cooking process. Both tuna packed in water and tuna packed in oil will work, though I personally prefer water-packed since it won’t make your casserole greasy. Albacore (white tuna) gives you larger, meatier chunks that stay together nicely, while chunk light tuna breaks down more but distributes flavor throughout the dish. Don’t worry about buying the most expensive brand – since this is a casserole with lots of other flavors, a basic store brand will do the job just fine.

Options for Substitutions

This comforting casserole is really forgiving when it comes to swaps and substitutions:

• Egg noodles: You can easily swap these for penne, rotini, or even elbow macaroni. Just keep the cooking time the same – the pasta will cook perfectly in the crockpot.
• Cream of mushroom soup: Try cream of celery or cream of chicken soup instead. For a lighter option, mix 1 cup of milk with 3 tablespoons of flour and add extra seasoning.
• Tuna: Canned salmon works great here, or you can use leftover cooked chicken for a different protein. If using chicken, shred it into bite-sized pieces.
• Canned mushrooms: Fresh mushrooms are actually better if you have them – just sauté them first for about 5 minutes. You can also skip them entirely if mushrooms aren’t your thing.
• Cheddar cheese: Swiss, mozzarella, or even a cheese blend will work just fine. The key is using something that melts well.
• Frozen peas: Frozen corn, green beans, or mixed vegetables are all good alternatives. You could also use fresh peas – just add them in the last 30 minutes of cooking.

Watch Out for These Mistakes While Cooking

The biggest mistake with crockpot tuna casserole is adding too much liquid, which can turn your noodles into mush – stick to the exact broth measurements since the canned soup and mushrooms will release additional moisture during cooking.

Another common error is adding the tuna too early in the process, as it can break apart and become dry, so wait until the last 30 minutes of cooking to fold it in gently.

Don’t forget to add the frozen peas during the final 15 minutes rather than at the beginning, since they only need a quick warm-through and will turn to paste if overcooked.

Finally, resist the urge to lift the lid frequently to check on progress – each peek releases heat and can add 15-20 minutes to your cooking time, leaving you with unevenly cooked noodles.

What to Serve With Crockpot Tuna Casserole?

This hearty tuna casserole is pretty much a complete meal on its own, but I love serving it with a simple side salad to add some fresh crunch to balance out all that creamy goodness. A basic mixed greens salad with cucumber, cherry tomatoes, and a light vinaigrette works perfectly and doesn’t compete with the rich flavors of the casserole. If you want something warm on the side, some buttered dinner rolls or garlic bread are great for soaking up any extra sauce. For a bit of color and extra veggies, steamed broccoli or green beans make nice additions that pair well with the mushrooms and peas already in the dish.

Storage Instructions

Refrigerate: This tuna casserole keeps really well in the fridge for up to 4 days in a covered container. The flavors actually get even better after sitting overnight, so it’s perfect for meal prep. I like to portion it out into individual containers for easy grab-and-go lunches throughout the week.

Freeze: You can freeze portions of this casserole for up to 3 months in freezer-safe containers or bags. Just make sure it’s completely cooled first, and leave a little room at the top since it’ll expand when frozen. I usually freeze it in family-sized portions so I can thaw exactly what I need.

Reheat: To warm it back up, just microwave individual portions for 1-2 minutes, stirring halfway through. For larger portions, cover with foil and bake at 350°F for about 20-25 minutes until heated through. You might want to add a splash of chicken broth if it seems a bit dry after reheating.

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 2000-2200
• Protein: 110-125 g
• Fat: 45-55 g
• Carbohydrates: 270-300 g

Ingredients

For the casserole:

• 12 oz uncooked egg noodles
• 1 can (10.5 oz) condensed cream of mushroom soup
• 2 cups chicken broth for slow cooker or 3.5 cups for pressure cooker
• 1 cup diced onion
• 3 cans (5 oz each) tuna, drained
• 2 tbsp italian blend seasoning
• 1/2 tsp salt
• 1/2 tsp ground black pepper
• 8 oz canned mushrooms, sliced and drained
• 1 1/2 cups frozen peas

For the topping:

• 1 cup shredded cheddar cheese
• Optional: 1/4 cup dry breadcrumbs

Step 1: Cook the Egg Noodles (Stovetop Method)

• 12 oz uncooked egg noodles

Bring a large pot of salted water to a boil.

Add the egg noodles and cook according to package instructions until just a little underdone (al dente).

Drain well and set aside for later use.

I always make sure not to overcook the noodles, as they’ll finish cooking in the casserole.

Step 2: Mix Together the Base Ingredients

• 1 can (10.5 oz) condensed cream of mushroom soup
• 2 cups chicken broth
• 3 cans (5 oz each) tuna, drained
• 1 cup diced onion
• 2 tbsp Italian blend seasoning
• 1/2 tsp salt
• 1/2 tsp ground black pepper
• cooked egg noodles (from Step 1)

In a large bowl, whisk together the cream of mushroom soup and 2 cups of chicken broth until smooth and creamy.

Add in the drained tuna, diced onion, Italian seasoning, salt, and black pepper.

Stir until everything is well combined.

Then gently fold in the undercooked noodles (from Step 1) until evenly coated with the sauce.

Step 3: Slow Cook the Casserole

Transfer the noodle mixture into your slow cooker.

Cover and cook on LOW for 3 to 4 hours or on HIGH for 1½ to 2 hours, stirring occasionally if possible, until everything is heated through.

This gentle cooking blends the flavors beautifully.

Step 4: Add Mushrooms, Peas, and Cheese

• 8 oz canned mushrooms, sliced and drained
• 1 1/2 cups frozen peas
• 1 cup shredded cheddar cheese

15 minutes before the cook time ends, lift the slow cooker lid.

Gently fold in the sliced mushrooms (drained) and frozen peas.

Stir in ½ cup of the shredded cheddar cheese until mixed throughout the casserole.

Top the casserole with the remaining ½ cup of cheese and replace the lid, allowing the cheese to melt into the casserole for the final 15 minutes.

I like to let the cheese bubble just a bit for extra flavor.

Step 5: Top with Breadcrumbs and Serve

• optional: 1/4 cup dry breadcrumbs

Once the cheese is melted and the casserole is hot, sprinkle the top with dry breadcrumbs just before serving, if desired.

Serve hot and enjoy!

One-Pot Crockpot Tuna Casserole

Delicious One-Pot Crockpot Tuna Casserole recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 1 hour hr

Cook Time 2 hours hrs 2 minutes mins

Total Time 3 hours hrs 2 minutes mins

Servings: 4

Calories: 2100

Ingredients Method

Ingredients

  

For the casserole:

• 12 oz uncooked egg noodles
• 1 can (10.5 oz) condensed cream of mushroom soup
• 2 cups chicken broth for slow cooker or 3.5 cups for pressure cooker
• 1 cup diced onion
• 3 cans (5 oz each) tuna, drained
• 2 tbsp Italian blend seasoning
• 1/2 tsp salt
• 1/2 tsp ground black pepper
• 8 oz canned mushrooms, sliced and drained
• 1 1/2 cups frozen peas

For the topping:

• 1 cup shredded cheddar cheese
• optional: 1/4 cup dry breadcrumbs

Method

 

1. Bring a large pot of salted water to a boil. Add the egg noodles and cook according to package instructions until just a little underdone (al dente). Drain well and set aside for later use. I always make sure not to overcook the noodles, as they'll finish cooking in the casserole.
2. In a large bowl, whisk together the cream of mushroom soup and 2 cups of chicken broth until smooth and creamy. Add in the drained tuna, diced onion, Italian seasoning, salt, and black pepper. Stir until everything is well combined. Then gently fold in the undercooked noodles (from Step 1) until evenly coated with the sauce.
3. Transfer the noodle mixture into your slow cooker. Cover and cook on LOW for 3 to 4 hours or on HIGH for 1½ to 2 hours, stirring occasionally if possible, until everything is heated through. This gentle cooking blends the flavors beautifully.
4. 15 minutes before the cook time ends, lift the slow cooker lid. Gently fold in the sliced mushrooms (drained) and frozen peas. Stir in ½ cup of the shredded cheddar cheese until mixed throughout the casserole. Top the casserole with the remaining ½ cup of cheese and replace the lid, allowing the cheese to melt into the casserole for the final 15 minutes. I like to let the cheese bubble just a bit for extra flavor.
5. Once the cheese is melted and the casserole is hot, sprinkle the top with dry breadcrumbs just before serving, if desired. Serve hot and enjoy!