Split turkey tenderloins in half horizontally. Sprinkle turkey with poultry seasoning. Coat a grill pan with cooking spray; heat pan over medium heat. Add turkey to hot pan; cook about 8 minutes or until no longer pink (165 degrees F), turning once.
Meanwhile, for gravy, in a small saucepan bring broth to boiling. In a small bowl whisk flour into the water until smooth; whisk into broth. Cook and stir over medium heat until thickened and bubbly. Reduce heat. Simmer for 2 minutes more, stirring constantly.
In a covered large saucepan cook cauliflower in a small amount of boiling salted water about 15 minutes or until tender; drain. Return cauliflower to hot saucepan; gently toss once or twice to dry off any excess moisture. In a food processor combine cauliflower, cream cheese, 1 tablespoon of the parsley, the salt, and pepper. Cover and process until nearly smooth.
To serve, place mashed cauliflower on toasted bread slices. Top with turkey and gravy. Sprinkle with the remaining 1 tablespoon parsley.