Tuna Tetrazzini Casserole

Tuna tetrazzini with mushrooms

Diana Rattray

Prep: 40 mins
Cook: 30 mins
Total: 70 mins
Servings: 6 servings
Yield: 1 casserole
Nutrition Facts (per serving)
483 Calories
20g Fat
44g Carbs
32g Protein
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Nutrition Facts
Servings: 6
Amount per serving
Calories 483
% Daily Value*
Total Fat 20g 25%
Saturated Fat 11g 57%
Cholesterol 78mg 26%
Sodium 773mg 34%
Total Carbohydrate 44g 16%
Dietary Fiber 5g 18%
Total Sugars 9g
Protein 32g
Vitamin C 9mg 44%
Calcium 301mg 23%
Iron 4mg 23%
Potassium 873mg 19%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)

Tuna and spaghetti team up with mushrooms and Parmesan cheese in this tuna tetrazzini recipe. It's a whole meal in one pot and can be prepared a day in advance, making it a convenient and tasty dish for a busy day. 

Serve the tuna casserole with crusty bread or biscuits and a simple tossed salad if you'd like.


  • 8 ounces thin spaghetti

  • 6 tablespoons (3 ounces) unsalted butter, divided

  • 16 ounces mushrooms, thinly sliced

  • 4 green onions, thinly sliced

  • 4 tablespoons all-purpose flour

  • 2 cups milk

  • 1/2 teaspoon salt, or to taste

  • 1/8 teaspoon freshly ground black pepper

  • 2 (4- to 6-ounce) cans tuna, drained and flaked

  • 1 cup frozen green peas, cooked and drained

  • 1 cup shredded Parmesan cheese, or 1/2 cup finely grated Parmesan cheese

  • 1 cup soft fresh bread crumbs

Steps to Make It

  1. Heat oven to 350 F. 

  2. Grease a 2 1/2 to 3-quart baking dish.

  3. Cook the spaghetti following the package directions in salted water. Drain and set aside.

  4. In a large saucepan over medium-low heat, melt 4 tablespoons of the butter. Add the mushrooms and saute, stirring, until mushrooms are browned and tender. Add the green onions and continue cooking for 1 minute. Stir in the flour until well blended. Gradually stir in the milk. Continue cooking, stirring constantly, until thickened. Add salt to taste and pepper. Stir in the flaked tuna and peas.

  5. Combine the tuna sauce mixture with the drained spaghetti until well blended. Turn the mixture into the prepared casserole. Sprinkle Parmesan cheese over the casserole.

  6. Melt the remaining 2 tablespoons of butter and toss with the bread crumbs. Sprinkle the buttered crumbs over the Parmesan layer.

  7. Bake in the preheated oven for 25 to 30 minutes, until lightly browned and bubbly.

Glass Bakeware Warning

For premade casseroles or leftovers that are in a glass baking dish and have been refrigerated, do not place directly into a hot oven as the glass can shatter. Instead, place any cold glass bakeware into a cold oven to warm up while it preheats. Or, allow the bakeware to rest outside of the fridge for 30 minutes to reach room temperature while the oven preheats.

Make Ahead Tip

Combine the tuna, spaghetti, vegetables, sauce up to a day in advance. Spoon into the baking dish; cover and refrigerate until about 30 minutes before you plan to bake it. Top with the Parmesan cheese and buttered bread crumbs and bake as directed, until the topping is browned and the filling is bubbling around the edges.