Preheat the oven to 350°F and spray a 13 x 9 inch baking dish with cooking spray. Set aside.
Cook the jumbo shells in salted water per the package directions until al dente. Drain well and cool enough to handle.
In a medium size mixing bowl use a hand mixer to whip together the prepared ranch dressing, softened cream cheese, dry Italian seasoning and red pepper flakes until fully combined.
Add the grated Parmesan cheese. chopped chicken, broccoli florets and 1 cup shredded mozzarella cheese Mix by hand until the ingredients are evenly distributed. Add granulated garlic, salt and black pepper. Mix well. (Taste and adjust amount of salt and pepper to your taste.)
Use a tablespoon to divide the filling between the shells, Place side by side in the baking dish.
Drizzle with Alfredo sauce and sprinkle the top with the remaining shredded cheese.
Bake for 35-40 minutes until golden and bubbly.
Sprinkle with chopped Italian parsley and serve immediately.