Preheat oven to 350.
To make your sauce in medium saucepan on stove add your butter and melt, once melted stir in your cream cheese until melted.
Add in your heavy cream, parmesan, garlic powder, salt and pepper.
Stir until thickened, remove from heat and set aside.
In the bottom of a 9"x13" baking dish spread a little bit of your Alfredo sauce.
In large bowl stir together your shredded chicken, broccoli and 1 cup of your sauce.
Fold in 1 cup mozzarella and Monterey Jack cheeses.
Stuff about 14 shells full of your chicken mixture.
Top with remaining sauce, remaining mozzarella and parmesan cheese.
Bake uncovered for about 15-20 minutes or until melted.
Sprinkle with parsley and serve.