• Preheat oven to 400°F.
• Butter a 3 quart casserole dish.

Cook mushrooms

• Cook the mushrooms in 1 1/2 tablespoons of the butter over medium heat, stirring, about 5 minutes. Set aside.
  8 ounces mushrooms

For butter cream sauce:

• In a large, heavy saucepan, melt 1/4 cup of butter. Stir in the flour, and cook the mixture over low heat, whisking constantly for one minute. Remove from the heat.
  1/2 cup gluten free all-purpose flour
• Slowly whisk in the broth until smooth.
  2 cups gluten free chicken broth
• Then whisk in the milk and heat on a medium flame, whisking constantly, simmering for one minute. Then stir in the sherry and simmer for one more minute.
  2 1/2 cups of milk, 2 tablespoons of sherry
• Remove from the heat. Flavor with lemon juice, nutmeg, salt and pepper to taste. Add the cooked spaghetti, turkey, and mushrooms to the sauce and toss.
  12 ounces gluten free spaghetti, 3 drops of lemon juice, 3 pinches of nutmeg, salt and pepper to taste, 3 cups leftover turkey
• Transfer the entire mixture to the buttered casserole.

Crumb topping

• In a small bowl combine parmesan and bread crumbs. Sprinkle the mixture evenly over the tetrazzini, and dot the top with the remaining 1 tablespoon of butter, cut into small pieces.
  1/3 cup parmesan, 1/3 cup gluten free panko breadcrumbs
• Bake on the middle rack of the oven until the sauce is bubbly and the top is golden, about 40 minutes.