In a large skillet melt butter over medium heat. Add mushrooms and onion and cook until translucent, about 5 minutes. Add flour and cook until bubbly, about 2 minutes. Add chicken broth gradually while stirring and bring to a boil. Cook until thickened. Remove from heat and add milk, heavy cream, parsley, salt, pepper, and nutmeg. Stir in spaghetti and turkey.
Pour mixture into a 13x9-inch baking dish. Cover with foil and refrigerate up to 24 hours.
Preheat your oven to 350ºF. Uncover the baking dish and sprinkle with parmesan cheese. Cover with foil and cook until heated through, about 50 minutes. Remove foil and cook 10 minutes more. Serve.
Notes
You can find cubed turkey in the deli section of your grocery store.
You can substitute half-n-half for the heavy cream and milk.
Perfect Pairing
Serve this classic casserole with Banana Pudding Parfaits to make this weeknight meal extra special.
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