Tuna Tetrazzini - Tuna and Spaghetti Casserole

Tuna Tetrazzini With Spaghetti and Mushrooms
Tuna Tetrazzini With Mushrooms. Photo: Diana Rattray
Ratings (18)
  • Total: 50 mins
  • Prep: 0 mins
  • Cook: 50 mins
  • Yield: 6 Servings
Nutritional Guidelines (per serving)
542 Calories
24g Fat
47g Carbs
33g Protein
(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 butter, divided
  • 16 ounces thinly sliced mushrooms
  • 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 cans (4 to 6 ounces each) tuna, drained and flaked
  • 1 cup frozen green peas, cooked and drained
  • 1 cup shredded natural Parmesan cheese or about 1/2 cup finely grated Parmesan cheese
  • 1 cup soft fresh bread crumbs

Steps to Make It

Heat oven to 350 F. 

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

Cook the spaghetti following the package directions. Drain and set aside.

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.

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.

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

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

Serves 6.

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.

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