Yield: 8 servings.
½ cup unsalted butter, divided
½ sweet onion, chopped
2 stalks celery, sliced
2 cloves garlic, minced
¼ cup all-purpose flour
4 cups chicken stock
2 cups heavy cream
4 ounces Swiss cheese, shredded
1 teaspoon salt
4 cups cooked turkey, shredded
1 pound spaghetti, cooked al dente
1 cup frozen peas
Salt and pepper to taste
1 cup panko bread crumbs
½ cup Parmesan, grated
Preheat oven to 400°. Prepare a 2-quart casserole dish or 13 x 9-inch pan with cooking spray.
Melt ¼ cup butter in a large skillet over medium heat. Add onion and celery; cook until translucent, about 5 minutes. Add garlic and cook for 1 minute. Sprinkle flour over the onion and celery and cook for 1 to 2 minutes more, stirring occasionally.
Whisk in chicken stock and heavy cream. Bring liquid to a strong simmer, whisking occasionally. Reduce heat and cook until mixture is slightly thickened, about 3 to 5 minutes. Stir in Swiss cheese and salt.
Add turkey, spaghetti, and frozen peas. Add more salt and pepper to taste, if desired. Transfer pasta mixture to prepared casserole dish.
In a medium skillet, melt remaining butter. Add bread crumbs and Parmesan, mix well, and cook until lightly toasted. Sprinkle bread crumb mixture over top of casserole.
Bake for 30 minutes or until hot and bubbling, and bread crumb topping is lightly browned.