Heat oven to 350°F. Spray 9-inch glass pie plate with cooking spray. Set aside.
In 10-inch skillet, heat sauce mix and uncooked pasta (from Hamburger Helper box), and milk and hot water to boiling, stirring occasionally. Reduce heat. Cover; simmer about 16 minutes, stirring occasionally, until pasta is tender. Remove from heat. Stir in cream cheese and Buffalo wing sauce until completely combined. Stir in chicken. Transfer mixture to pie plate. Top with cheese.
Bake about 10 minutes or until cheese is melted and filling is slightly bubbly. Serve with celery sticks and tortilla chips for dipping.