Big Tuna Casserole is not your momma’s typical bland bake (love you anyway, mom). It has big flavor, big crunch, and well, it’s pretty big–it can feed at least six people. You have to have a pretty hefty appetite, too, when digging into the creamy, savory roux that covers soft, fluffy egg noodles and flakey, tender tuna topped with the perfect bread crumb crunch. Sounds mighty filling, doesn’t it?! I guess you could say this delicious Big Tuna Casserole is a pretty big deal (mom will agree, too)!

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  • 1/2 cup water
  • 1 teaspoon chicken bouillon granules
  • 1 (9-ounce) package frozen cut green beans
  • 1 cup onion, chopped
  • 1 cup fresh mushrooms, sliced
  • 1/4 cup celery, chopped
  • 1 garlic clove, minced
  • 1/2 teaspoon dill weed
  • 1/2 teaspoon salt
  • 1/8 teaspoon pepper
  • 4 teaspoons cornstarch
  • 1 1/2 cups whole milk, cold
  • 1/2 cup Swiss cheese, shredded
  • 1/4 cup mayonnaise
  • 2 1/2 cups egg noodles, cooked and drained
  • 1 (12-ounce) can light tuna in water, drained and flaked
  • 1/3 cup dry bread crumbs
  • 1 tablespoon butter


Step 1 –Preheat the oven to 350 degrees F.

Step 2 –Grease a 2 1/2-quart baking dish.

Step 3 –In a large saucepan, bring the water and the bouillon granules to a boil; stir until the bouillon is dissolved.

Step 4 –Add the green beans, the onion, the mushrooms, the celery, the garlic, the dill weed, the salt, and the pepper to the bouillon mixture.

Step 5 –Bring the veggie mixture to a boil.

Step 6 –Lower the heat, cover the saucepan, and simmer until the vegetables are tender, about 5 minutes.

Step 7 –In a small bowl, combine the cornstarch and the milk until smooth.

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Step 8 –Gradually add the milk mixture into the veggie mixture.

Step 9 –Bring the milk and veggie mixture to a boil.

Step 10 –Cook and stir the veggie mixture until thickened, about 2 minutes.

Step 11 –Transfer the thickened veggie mixture from the heat.

Step 12 –Stir the cheese and the mayonnaise into the veggie mixture.

Step 13 –Fold the noodles and the tuna into the veggie mixture.

Step 14 –Pour the tuna mixture into the prepared baking dish.

Step 15 –In a small skillet, brown the bread crumbs in the butter.

Step 16 –Sprinkle the browned bread crumbs over the casserole.

Step 17 –Bake, uncovered, until heated through, about 25-30 minutes.

Step 18 –Serve.