Cook turkey sausage in a nonstick skillet over medium-high heat until browned, stirring until it crumbles. Drain, if necessary. Add soup; stir well.
Combine 1 cup milk and flour, stirring until smooth. Add milk mixture to turkey mixture; bring to a boil. Stir in peas and carrots. Reduce heat, and cook, uncovered, 2 to 3 minutes or until turkey mixture is slightly thickened, stirring occasionally. Place 1 cup mixture into each of 6 (8-ounce) ovenproof casserole dishes coated with cooking spray.
Prepare potatoes according to package directions, using remaining 1 1/2 cups milk. Top each casserole with 1/2 cup mashed potato mixture. Sprinkle with paprika, if desired. Bake at 400° for 15 to 20 minutes or until turkey mixture is thoroughly heated and potatoes are lightly browned. Sprinkle with chopped parsley, if desired.