Heat oven to 375°F. Spray 12" x 8" -inch glass baking dish with cooking spray.
Place frozen pierogies and water in medium microwave-safe bowl; cover with plastic wrap. Microwave on High 2 minutes; stir. Continue microwaving on High 1 1/2 to 2 minutes until thawed.
Place pierogies evenly in casserole. Top with sausage.
In medium bowl, mix cream cheese, sour cream, and chicken broth with whisk. Stir in 1/2 cup of the Cheddar cheese and 1/3 cup of the green onions (reserve remaining onions for topping). Pour cheese mixture evenly over pierogies. Cover with foil; bake 22 to 27 minutes or until center is heated through and temperature reaches 165°F.
Uncover, and top with remaining cheese; bake 3 to 5 minutes or until cheese is melted. Sprinkle with reserved green onions.