Chicken Tetrazzini

Instructions

1. Prepare the pasta
   Preheat oven to 375°F (190°C). Cook the spaghetti in a large pot of salted water until al dente, about 2 minutes less than package directions. Drain and set aside.
2. Sauté the vegetables
   In a large skillet over medium heat, melt 2 tablespoons of butter. Add mushrooms and cook until they release their moisture and begin to brown, about 5-7 minutes. Add onions and cook until softened, about 3-4 minutes. Add garlic and cook for 30 seconds until fragrant. Season with salt and pepper. Transfer to a bowl and set aside.
3. Make the sauce
   In the same skillet, melt the remaining 2 tablespoons of butter over medium heat. Sprinkle in the flour and whisk constantly for 1-2 minutes to make a roux. Gradually whisk in the chicken broth, followed by milk and cream. Bring to a simmer and cook, whisking frequently, until the sauce thickens, about 5-7 minutes. Season with salt and pepper to taste.
4. Combine the ingredients
   Reduce heat to low and add the cooked mushroom mixture, shredded chicken, frozen peas, and 1 cup of Parmesan cheese to the sauce. Stir until well combined and cheese is melted. Gently fold in the cooked spaghetti until everything is evenly coated.
5. Assemble and bake
   Transfer the mixture to a greased 9x13 inch baking dish. In a small bowl, combine the breadcrumbs with the remaining ½ cup of Parmesan cheese. Sprinkle this mixture evenly over the top of the casserole. Bake in the preheated oven until bubbly and golden brown on top, about 25 minutes.
6. Rest and serve
   Remove from the oven and let stand for 10 minutes. Sprinkle with chopped parsley before serving. This rest time allows the casserole to set and makes it easier to serve.