Cook rice according to package directions. Set aside.
Brown sausage in large skillet over medium heat about 10 minutes, stirring until sausage crumbles and is no longer pink. Add onion and red bell pepper to sausage mixture, and sauté 3 minutes or until vegetables are tender. Drain. Return sausage mixture to skillet over medium-high heat, and add mushrooms and water chestnuts. Sauté 3 minutes or until mushrooms are tender.
Whisk in flour and pepper; cook, whisking constantly, 1 minute. Whisk in chicken broth and milk; cook 7 to 8 minutes or until thickened and bubbly. Remove from heat. Stir together rice, sausage mixture, and turkey. Transfer to a lightly greased 13- x 9-inch baking dish. Bake at 350° for 25 to 30 minutes or until thoroughly heated. Top with fresh chopped parsley, if desired.