Lightly spray large skillet with cooking spray; heat on med-high heat. Add onion; cook until tender, stirring often. Add cream cheese, broth and mustard; mix well until creamy. Remove from heat; set aside.
Lightly spray 13x9-inch baking dish with cooking spray. Toss potatoes with cream cheese mixture and spoon into prepared baking dish. Combine crushed crackers, parmesan cheese, melted butter and parsley; sprinkle evenly over potatoes.
Bake 50 minutes to 1 hour until potatoes are tender. Let stand 5 minutes before serving. Enjoy!
*For added flavor/color substitue 1 medium sweet potato for 1 white potato.