Creamy Tuna Casserole for a Crowd

I didn’t make my first tuna casserole until I was hosting a potluck and realized I’d invited way too many people. My go-to recipe fed six, and I had twenty mouths to feed. That’s when I learned the beauty of a good crowd-sized casserole.

The trick isn’t just doubling or tripling the recipe—that can get messy fast. You need to think about your baking dish size and cooking time. But once you figure it out, tuna casserole for a crowd is actually easier than making individual portions. One pan, everyone’s happy, and you’re not stuck making three separate batches while your guests wait around hungry.

What Kind of Tuna Should I Use?

For a crowd-sized casserole like this, canned tuna is definitely the way to go, and you’ll want to stick with water-packed rather than oil-packed to keep the casserole from getting greasy. Solid white albacore tuna will give you a milder flavor and firmer texture, while chunk light tuna is more budget-friendly and works just as well when you’re feeding a lot of people. Since you’re using so much tuna in this recipe, buying store-brand cans can save you quite a bit of money without sacrificing taste. Just make sure to drain the tuna really well before adding it to your casserole – nobody wants a watery dish!

Options for Substitutions

When you’re cooking for a crowd, it’s helpful to know what you can swap out if needed:

• Egg noodles or penne: You can use any pasta shape you like – rotini, shells, or even elbow macaroni work great. Just cook according to package directions and drain well before mixing.
• Butter: Margarine works fine as the recipe suggests, or you can use half butter and half olive oil to cut down on saturated fat without losing flavor.
• Canned tuna: If you’re short on tuna, you can replace up to half of it with cooked chicken breast. Rotisserie chicken is a time-saver for large batches. You could also use canned salmon for a different flavor profile.
• Mild cheese: The recipe is flexible with cheese types, so use what you have or what’s on sale. Just stick with mild varieties so the cheese doesn’t overpower the tuna.
• Frozen peas: Swap these out for frozen mixed vegetables, green beans, or corn if you prefer. You can also use fresh vegetables, but add them earlier in the cooking process so they soften properly.
• Chicken stock: Vegetable stock works as a substitute, or you can use all milk for a creamier casserole – just add a bit more salt to make up for the missing stock flavor.

Watch Out for These Mistakes While Cooking

The biggest mistake when making tuna casserole for a crowd is overcooking your noodles during the initial boil – cook them just until they’re slightly underdone (about 2 minutes less than package directions) since they’ll continue cooking in the oven and you don’t want mushy pasta.

When making the sauce, add your flour gradually while whisking constantly to avoid lumps, and make sure the mixture reaches a gentle simmer before adding the cheese so it melts smoothly without becoming grainy.

Don’t skip draining your tuna thoroughly – excess water will make your casserole watery and dilute the flavors, so press the tuna gently with paper towels after draining.

Since you’re feeding a crowd, use multiple shallow pans instead of one deep dish so the casserole heats evenly and develops a nice golden top, and check the internal temperature reaches 165°F in the center before serving.

What to Serve With Tuna Casserole?

Since tuna casserole is already a complete meal with pasta, protein, and veggies, I like to keep the sides simple and fresh. A crisp green salad with a tangy vinaigrette cuts through the richness of the creamy casserole and adds a nice contrast. Dinner rolls or garlic bread are always a hit for soaking up any extra sauce, and they’re easy to make in large batches when you’re feeding a crowd. If you want to add more vegetables to the table, roasted green beans or steamed broccoli work great alongside this dish without overwhelming the meal.

Storage Instructions

Store: This big batch of tuna casserole keeps well in the fridge for up to 3 days in airtight containers. Since you’re feeding a crowd, you might want to divide it into smaller portions so people can grab what they need throughout the week.

Freeze: You can definitely freeze portions of this casserole for up to 2 months. Just make sure it’s cooled completely first, then pack it in freezer-safe containers or heavy-duty foil pans. This is great if you’re prepping for a big event and want to get ahead.

Reheat: Warm it up in the oven at 350°F covered with foil until heated through, about 30-40 minutes depending on portion size. You can also microwave individual servings for a few minutes, stirring halfway through to heat evenly.

Preparation Time	30-45 minutes
Cooking Time	3 hours
Total Time	3 hours 30-45 minutes
Level of Difficulty	Medium

Estimated Nutrition

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

• Calories: 33,000-36,000
• Protein: 2,600-2,900 g
• Fat: 1,300-1,500 g
• Carbohydrates: 4,200-4,600 g

Ingredients

For the noodles:

• 5 lb egg noodles (or penne pasta)

For the creamy sauce:

• 2 lb celery (chopped into 1/4-inch pieces)
• 2 gallons chicken broth (or use 3/4 cup Better Than Bouillon for convenience)
• 2 gallons whole milk (room temperature)
• 2 lb onion (chopped into 1/4-inch pieces)
• 3 1/2 cups all-purpose flour (I use King Arthur)
• 4 lb shredded mild cheese (American, mild cheddar, Monterey Jack, or Colby blend)
• 1 lb unsalted butter (Kerrygold preferred for rich flavor)

For seasoning and mix-ins:

• 1 tbsp ground black pepper (freshly ground preferred)
• 1 cup dried parsley flakes (or fresh parsley for brighter flavor)
• 2 tsp kosher salt
• 3 lb frozen green peas (Birds Eye or similar quality brand)
• 1 1/2 cups lemon juice (freshly squeezed for best taste)

For the tuna filling:

• 13 lb canned tuna in water (42 cans of 5 oz each, drained and flaked)

Step 1: Prepare Mise en Place and Cook Pasta

• 5 lb egg noodles
• 2 lb celery, chopped into 1/4-inch pieces
• 2 lb onion, chopped into 1/4-inch pieces
• 1 1/2 cups lemon juice, freshly squeezed

While you’re gathering ingredients, fill a large pot with salted water and bring it to a boil.

Chop the celery and onion into uniform 1/4-inch pieces—this consistency is important for even cooking and texture.

Once the water boils, add the egg noodles and cook for exactly 6 minutes (they’ll finish cooking in the oven, so you want them slightly underdone).

Drain the noodles and set aside.

I always use fresh lemon juice squeezed just before cooking rather than bottled, as it makes a noticeable difference in brightness.

Step 2: Build the Cream Sauce Base

• 1 lb unsalted butter
• 2 lb celery, chopped
• 2 lb onion, chopped
• 3 1/2 cups all-purpose flour

In a very large pot or Dutch oven, melt the butter over medium heat.

Add the chopped celery and onion, stirring occasionally, and cook for 5-6 minutes until the vegetables are softened and fragrant—this builds foundational flavor.

Sprinkle the flour over the vegetables and stir constantly for 1-2 minutes to create a roux, which will thicken your sauce.

This step is crucial: the roux needs to cook briefly to eliminate the raw flour taste without browning.

Step 3: Create the Sauce and Melt Cheese

• 2 gallons whole milk, room temperature
• 2 gallons chicken broth
• 2 tsp kosher salt
• 1 tbsp ground black pepper
• 1 cup dried parsley flakes
• 4 lb shredded mild cheese

Slowly pour in the room-temperature milk while stirring constantly to avoid lumps—cold milk can cause clumping, so room temperature is essential.

Then add the chicken broth, stirring well to combine.

Season with kosher salt, freshly ground black pepper, and dried parsley.

Bring the mixture to a gentle simmer over medium heat, stirring frequently.

Once simmering, slowly add the shredded cheese in batches, stirring after each addition until fully melted and incorporated.

Continue cooking for about 30 minutes, stirring occasionally, until the sauce thickens enough to coat the back of a spoon.

I prefer Kerrygold butter here because its rich, slightly golden color and higher fat content create a more luxurious sauce.

Step 4: Combine All Components

• cooked noodles from Step 1
• 3 lb frozen green peas
• 13 lb canned tuna in water, drained and flaked
• lemon juice from Step 1
• cream sauce from Step 3

Remove the thickened cream sauce from heat.

Add the cooked noodles from Step 1, along with the frozen peas (no need to thaw them), drained and flaked tuna, and lemon juice.

Stir gently but thoroughly until everything is evenly distributed and coated with sauce.

The residual heat will warm the peas through.

This is a large volume, so take your time to ensure all the tuna is broken up nicely and incorporated throughout.

Step 5: Transfer and Prepare for Baking

• combined casserole mixture from Step 4

Divide the casserole mixture evenly into large baking pans or hotel pans.

Cover tightly with foil or lids to prevent drying during the long bake.

At this point, you can refrigerate the casseroles for up to 24 hours before baking, or proceed directly to the oven if baking immediately.

Step 6: Bake Covered, Then Finish Uncovered

Preheat your oven to 400°F.

Place the covered casseroles on the middle racks and bake for 2.5 hours—the long, gentle bake allows flavors to meld and ensures the dish heats through completely, especially important for this volume.

After 2.5 hours, carefully remove the foil or lids and bake uncovered for an additional 30 minutes until the top is lightly golden and the edges are bubbling gently.

This final uncovered period allows the top to develop a slight crust while keeping the interior creamy.