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A close-up shot of a creamy serving of Chicken Tetrazzini with mushrooms and parsley being lifted from a baking dish.

Creamy Chicken Tetrazzini Casserole

This comforting and hearty casserole features tender shredded chicken, al dente spaghetti, savory mushrooms, and sweet peas, all enveloped in a rich, creamy Parmesan sauce and baked to golden perfection under a crispy panko topping.
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Prep Time 25 minutes
Cook Time 30 minutes
Total Time 55 minutes
Servings: 6 servings
Course: Main Course
Cuisine: American, Italian-American
Calories: 750
Ingredients Equipment Method Notes

Ingredients
  

For the Chicken & Pasta
  • 2 lbs boneless, skinless chicken breasts cooked and shredded or diced, or use rotisserie chicken
  • 12 oz spaghetti or linguine broken into thirds
  • 1 tbsp salt for pasta water
  • 1 tsp olive oil for tossing pasta
For the Creamy Sauce & Vegetables
  • 4 tbsp unsalted butter
  • 1 cup yellow onion diced
  • 8 oz cremini mushrooms sliced
  • 2 cloves garlic minced
  • 1/4 cup all-purpose flour
  • 4 cups chicken broth low sodium
  • 1 cup heavy cream
  • 1/2 cup grated Parmesan cheese plus more for serving
  • 1/4 cup dry white wine e.g., Pinot Grigio or Chardonnay, optional
  • 1 cup frozen green peas
  • 1/2 cup fresh parsley chopped, plus more for garnish
  • 1 tsp dried Italian seasoning
  • 1/2 tsp salt or to taste
  • 1/4 tsp black pepper or to taste
For the Topping
  • 1/2 cup panko breadcrumbs
  • 2 tbsp unsalted butter melted

Equipment

  • Large Pot
  • Large Skillet or Dutch Oven
  • 9x13 inch baking dish
  • Whisk
  • Cutting board
  • Knife

Method
 

Prepare Ingredients
  1. Preheat your oven to 375°F (190°C). Grease a 9x13 inch baking dish with butter or cooking spray.
  2. If using raw chicken breasts, cook them now: In a large pot, bring salted water to a boil. Add the chicken breasts and cook for 15-20 minutes, or until cooked through. Remove, let cool slightly, then shred or dice. Set aside.
  3. In the same pot of boiling salted water, add the broken spaghetti. Cook according to package directions until al dente. Drain well and toss with 1 tsp olive oil to prevent sticking. Set aside.
Make the Creamy Sauce
  1. In a large skillet or Dutch oven, melt 4 tablespoons of unsalted butter over medium heat. Add the diced yellow onion and cook until softened, about 5-7 minutes.
  2. Add the sliced mushrooms to the skillet and cook, stirring occasionally, until they release their liquid and start to brown, about 5-8 minutes. Stir in the minced garlic and cook for another minute until fragrant.
  3. Sprinkle the flour over the vegetables and stir continuously for 1 minute to cook out the raw flour taste.
  4. Gradually whisk in the chicken broth, then the heavy cream, ensuring no lumps form. Bring the mixture to a gentle simmer, stirring frequently, until the sauce thickens, about 5-7 minutes.
  5. Remove the skillet from the heat. Stir in 1/2 cup grated Parmesan cheese, dry white wine (if using), dried Italian seasoning, 1/2 tsp salt, and 1/4 tsp black pepper. Taste and adjust seasoning as needed.
Assemble and Bake Casserole
  1. In a large mixing bowl, combine the cooked spaghetti, shredded chicken, frozen green peas, and chopped fresh parsley. Pour the creamy sauce over the mixture and toss gently until everything is evenly coated.
  2. Transfer the chicken and pasta mixture into the prepared 9x13 inch baking dish, spreading it out evenly.
  3. In a small bowl, combine the panko breadcrumbs and 2 tablespoons of melted unsalted butter. Sprinkle this mixture evenly over the top of the casserole.
  4. Bake for 25-30 minutes, or until the casserole is bubbly around the edges and the panko topping is golden brown and crispy.
  5. Remove from oven and let rest for 5-10 minutes before serving. Garnish with additional fresh parsley or Parmesan cheese, if desired.

Notes

Leftover Creamy Chicken Tetrazzini Casserole can be stored in an airtight container in the refrigerator for up to 3-4 days. Reheat gently in the oven or microwave. For a richer flavor, consider adding a pinch of nutmeg to the sauce. You can also customize by adding other vegetables like bell peppers or spinach.