Cook and drain pasta as directed on package. Rinse with cold water; drain.

Heat oven to 350ºF

Add 4oz butter and flour to 3-quart saucepan. Cook over medium-low heat, stirring constantly, for 2 minutes. Gradually add broth and half-and-half, whisking well to avoid lumps. Cook until smooth and bubbly, about 3 minutes, stirring occasionally. When smooth, stir in spices.

Combine turkey, cooked pasta, and sauce in an ungreased 13x9 baking dish. Stir in olives, mushrooms and cheddar cheese. Add sour cream to mixture until desired creaminess.

Sprinkle topping over casserole. Place in oven and bake for about 25-30 minutes. If desired, broil briefly to brown top.